5 ms·

CS2 Fog Of War: Server-sided anti-wallhack occlusion culling for CS2 servers

104 points by LorenDB 3mo ago

landr0id 3mo ago
I wonder how often wall hacks are actually used in high-level competitive play by cheaters vs ESP. ESP seems like the better route to avoid manual review flagging suspicious activity. Audible cues (which this currently does not mitigate, and I'm not sure it can) are things that can genuinely separate players by skill and you'd think someone running such a cheat just has very good hearing. >CS2FOW uses static baked map geometry. Dynamic occluders such as doors, breakables, props, smokes, particles, and projectiles are intentionally out of scope for now. Market window on Mirage just became more powerful on these servers :) Very cool project nonetheless.
- deleted 3mo ago
  [deleted]
- aidenn0 3mo ago
  I didn't know what ESP was; from some googling, it appears to notify you when someone is aiming at you?
  - landr0id 3mo ago
    Yeah my bad for not defining it. "Extra-Sensory Perception", basically as you said I believe is the most common feature -- but in general I think encompasses cheats that generally boost your "senses". So it could use audio to visually draw on your screen/radar where the sound came from. The screenshot in this repo is kind of similar to wallhacks, but you could imagine this could easily be extended to show dropped items and the 3D audio location: https://github.com/ryanjpwatts/esp-analysis https://github.com/ryanjpwatts/esp-analysis
dvt 3mo ago
This has been done before in both 1.6 as well as Source. I helped with some of these implementations back in the late-2000s when I was playing professionally and I even tried to kickstart an anti-cheat hardware solution about a decade ago[1].. spent way too much time working on some of these problems. The main issue with occlusion was slightly increased latency, visual jitter because of interpolation (especially around corners), and a few other more technical problems[2]. It's good enough for public servers, but not tenable in serious competition. Cheating has always been a problem in FPSs, and it likely won't go away. That's why premier competitions have always been on LAN. [1] https://www.pcgamer.com/introducing-gameref-the-anti-cheat-hardware/ https://www.pcgamer.com/introducing-gameref-the-anti-cheat-h... [2] Hard to fully obfuscate audio sources, hard to obfuscate hitboxes since you still need them for collision checking (e.g. if a grenade bounces off an enemy player behind a wall—the server does not do all physics for all clients), and this is on top of the engine itself sometimes requiring actual entities, so you're stuck with these dummy entities in memory, and so on.
- davedx 3mo ago
  Why on earth don't the producers of the game implement this? It sounds trivial to do?
  - xeonmc 3mo ago
    The many tradeoffs involved are not trivial, this can only feasibly work well on LAN. This is the reason why Valorant is the least playable among all competitive shooters if your internet is anything lesser than Google campus fiber, ironically in spite of having even-slower-than-CS movement physics on its side to mask the problem. Riot conveniently cherry picks the best case scenario and handwaves the actual technical tradeoffs in their smug "we solved peeker's advantage!" engineering blog posts that are really just barely-disguised monorail Gish gallop.
    - efilife 3mo ago
      Yup, I just reread the post you are talking about (https://www.riotgames.com/en/news/peeking-valorants-netcode https://www.riotgames.com/en/news/peeking-valorants-netcode) and it really seems like just endless fluff and no real solutions. Reading this post is almost unbearable and it all just comes down to this part: > We built Riot Direct, our own internet backbone, to minimize network routing delays and processing time across the internet. > We’re standing up VALORANT servers around the world, ultimately aiming to deliver 35ms ping to 70% of our player base. > We optimized our servers to provide a smooth 128 server tickrate to all players. > We optimized the VALORANT game client to run at 60FPS on most machines from this decade and higher framerates for players with high refresh rate monitors. > We run clients and servers running with minimal buffering, targeting one buffered frame of movement data for clients and an average of half a frame of movement data on servers. This seems like basic stuff that every other game does.
    - tharkun__ 3mo ago
      Hah, this reminds me of my "ancient past". This must have been CS 1.4 or 1.5 times. I had terrible internet. 36k modem times, super high (ish - 150+ms at the very least, been a while, don't quote me, maybe it was way higher even?) ping to a server that had all the custom maps I loved. I got accused of cheating. I didn't. Simply a result of CS/HL netcode. I was able to "run circles" around others. Something in that version favored my local client view of things I suppose. I literally just went around corners and if there was an enemy I circled them while driving bullets into them w/ my P90. They died without even really seeing me (from what they were saying). On my end everything looked smooth and normal. This tactic never worked all that well on servers where I had the usual <120ms ping. I guess never mind at <15ms :)
xeonmc 3mo ago
> Does it cause pop-in when peeking? The goal is early reveal, not exact last-millisecond reveal. CS2FOW predicts using movement and ping, reveals enemies slightly before exact visibility, and keeps revealed enemies visible briefly. This intentionally leaks a small near-corner window to avoid late pop-in. This fails to address the main point of the "pop-in" issue relevant to fog of war systems, which is that it is the victim of the peek that gets the worst pop-in effect, the peeker much less so. The aggressive peeker gets the benefit of the early-prediction from the server since they're the initiator of the movement, whereas the victim only begins to receive the information after the peeker has already gotten two network roundtrips worth of early prediction.
- webstrand 3mo ago
  Interesting, could it be mitigated by the server doing its own prediction and defogging the peeker early? Or is lag prediction in CS2 not entirely client-sided.
  - xeonmc 3mo ago
    It's more that momentum-based defogging means that the peeker has control over how to manipulate the server's prediction, whereas the victim who is already disadvantaged by network latency now gets an additional penalty of the movement initiation being not telegraphed. To solve this, the fog of war would need to use purely positional near-edge tolerances, which defeats the entire purpose of fog of war to begin with, which is the pre-aiming reaction time advantage of tracking the peeker through walls in addition to having a farther lever point from the cover than the peeker.
- bakies 3mo ago
  Why wouldn't you just send the positions to both clients in the same tick? Seems trivial to solve.
  - dvt 3mo ago
    "Same tick" is a misnomer for a few reasons. First of all, games use UDP, which is basically a "fire and forget" protocol (which means packets get dropped routinely). Second of all, realtime games use some interpolation/prediction to make up for latency (and aforementioned dropped packets). So it's sort of a "relativistic" temporal system, not a linear "oh now you're at t=1, now you're at t=2" kind of timeline. And there's all kinds of complicated ways you create concensus between multiple clients, between server and clients, etc. (A lot of this remains an active research area.)
szmarczak 3mo ago
This is good. However, it still sends info about the players ~200ms ahead which still makes you lose.
Unkn0wn-d 3mo ago
[dead]
nyeah 3mo ago
Wallhack is locked into the DNA of CS for some reason. The most common defense by far is mass denial. For the great majority of players that seems to be good enough.
- frollogaston 3mo ago
  I'm fine as long as the game is somewhat evenly matched, and not fine if it's not. With or without cheating. Then whatever cheaters they can catch and shadowban, great. Smurfing is a way bigger problem anyway, cause some people treat the game like a job and will beat you more reliably than cheaters.
- ultimafan 3mo ago
  Not just CS, I don't think people realize how prevalent cheating is in any multiplayer game. The issue is compounded by the fact that many high skill ceiling games are plagued by "micro cheats" being used by players that are already fairly decent at the game even without them, making it borderline impossible for casual players to tell if what just happened to them was a fair skill gap or someone cheating. I don't play multiplayer games anymore for that reason. Too easy to go on an emotional tilt where you feel like you're suffering from paranoia and suspecting too many players of cheating. It's absolutely ruined competitive games for me.
- toilet 3mo ago
  Get good
lousken 3mo ago
Why hasn't valve poured a billion or two on fixing this concept and implementing it?
- charcircuit 3mo ago
  >Release Notes for 5/26/2015 >– Added trace-based visibility checks to prevent networking invisible enemy players. https://blog.counter-strike.net/2015/05/11988 https://blog.counter-strike.net/2015/05/11988
  - jamesfinlayson 3mo ago
    That's for Counter-Strike: Global Offensive - different engine.
    - charcircuit 3mo ago
      They are forks of the same engine. Presumably this was ported as part of the CS2 update to CSGO.
      - jamesfinlayson 3mo ago
        Not sure - one of the other comments said it wasn't because Source uses BSP and Source 2 uses meshes.
Xeoncross 3mo ago
Moving away from the technical solution space - I'm curious, have their been any games (or communities) with a high entry fee/deposit (e.g. $500 USD) to join kept in escrow and lost in the event you're discovered to be cheating? There are plenty more questions like paying for mods/review, securing the money, paying for servers, etc.. but my basic question is if cost of entry exceeds cost of reward from cheating has ever been attempted in a game. Apparently buying a new copy of a $10-20 game isn't enough to keep people away from cheats. Less so when there is prize money on the line or skins (e.g. CS2) worth $100k.
- lachiflippi 3mo ago
  >e.g. $500 USD I've seen private cheats for games with less-than-terrible anticheats charge that monthly, if not weekly. You're underestimating how much people are willing to pay to play with cheats, and overestimating how much regular people are willing to pay to play against players without them.
  - frollogaston 3mo ago
    Yeah you'll deter legit players with the escrow way before you'll deter cheaters. It's a good thought but probably not going to work.
- frollogaston 3mo ago
  Csgo became free at some point, and I remember the amount of smurfing increasing a lot then. Have rarely noticed cheaters, but smurfs are just as bad if not worse. They do at least require new accounts to waste some time playing deathmatch to be eligible for competitive.
MatheusFelipe 3mo ago
Why doesn't Valve implement this natively?
- cedws 3mo ago
  I think there’s a good possibility that they’re intentionally not fixing it, cheaters blatantly using wall hack are easy to root out and ban.
dabber21 3mo ago
I wonder if it could spawn "ghost players" in places no player could be to detect reaction
- bob1029 3mo ago
  Honeypot & statistics are a much more interesting avenue of anti-cheat to me. The most egregious cheaters tend to get banned the most quickly with these techniques (e.g. a 200-1 K/D ratio = a lot of samples per unit time). When it comes to cheating in video games, I subscribe more to the Dune philosophy than the LOTR philosophy. The ends (experience) definitely justify the means. Making sure that all cheaters are punished ~equally regardless of the effect of their infractions is fantastic in principle, but I'd rather if we could simply remove the ones that are obviously & openly ruining the experience. False positives suck, but there is no reason to pander to the .01% performers if you are trying to keep a multiplayer game community alive. Esports has demonstrated this is a terrible approach. We had community servers that would ban people simply for being too good before all the matchmaking stuff started up. The anti-cheat was vibes based and arguably superior to anything going on today. It wasn't "fair", but it was generally a much better experience as a player.
- skimdesk 3mo ago
  There was research on this published by Activision [1]. Spawning fake enemies behind the users back, inside walls, etc. The players who react to fake enemies self-identify as cheaters. [1]: https://www.activision.com/cdn/research/hallucinations https://www.activision.com/cdn/research/hallucinations
aucisson_masque 3mo ago
To me, the best anti cheat are the one you put in the game design. There is only one 'fps' I play, it's called holdfast and is about Napoleonic warfare. Muskets are so inaccurate that having a wallhack or an aimbot would be complete nonsense. There are still people who cheat in other way, but it's extremely limited. Cheaters killed 90% of the multiplayer game to me.

104 points by LorenDB 3mo ago

I wonder how often wall hacks are actually used in high-level competitive play by cheaters vs ESP. ESP seems like the better route to avoid manual review flagging suspicious activity. Audible cues (which this currently does not mitigate, and I'm not sure it can) are things that can genuinely separate players by skill and you'd think someone running such a cheat just has very good hearing. >CS2FOW uses static baked map geometry. Dynamic occluders such as doors, breakables, props, smokes, particles, and projectiles are intentionally out of scope for now. Market window on Mirage just became more powerful on these servers :) Very cool project nonetheless.

deleted 3mo ago
[deleted]
aidenn0 3mo ago
I didn't know what ESP was; from some googling, it appears to notify you when someone is aiming at you?
- landr0id 3mo ago
  Yeah my bad for not defining it. "Extra-Sensory Perception", basically as you said I believe is the most common feature -- but in general I think encompasses cheats that generally boost your "senses". So it could use audio to visually draw on your screen/radar where the sound came from. The screenshot in this repo is kind of similar to wallhacks, but you could imagine this could easily be extended to show dropped items and the 3D audio location: https://github.com/ryanjpwatts/esp-analysis https://github.com/ryanjpwatts/esp-analysis

dvt 3mo ago

This has been done before in both 1.6 as well as Source. I helped with some of these implementations back in the late-2000s when I was playing professionally and I even tried to kickstart an anti-cheat hardware solution about a decade ago[1].. spent way too much time working on some of these problems. The main issue with occlusion was slightly increased latency, visual jitter because of interpolation (especially around corners), and a few other more technical problems[2]. It's good enough for public servers, but not tenable in serious competition. Cheating has always been a problem in FPSs, and it likely won't go away. That's why premier competitions have always been on LAN. [1] https://www.pcgamer.com/introducing-gameref-the-anti-cheat-hardware/ https://www.pcgamer.com/introducing-gameref-the-anti-cheat-h... [2] Hard to fully obfuscate audio sources, hard to obfuscate hitboxes since you still need them for collision checking (e.g. if a grenade bounces off an enemy player behind a wall—the server does not do all physics for all clients), and this is on top of the engine itself sometimes requiring actual entities, so you're stuck with these dummy entities in memory, and so on.

davedx 3mo ago
Why on earth don't the producers of the game implement this? It sounds trivial to do?
- xeonmc 3mo ago
  The many tradeoffs involved are not trivial, this can only feasibly work well on LAN. This is the reason why Valorant is the least playable among all competitive shooters if your internet is anything lesser than Google campus fiber, ironically in spite of having even-slower-than-CS movement physics on its side to mask the problem. Riot conveniently cherry picks the best case scenario and handwaves the actual technical tradeoffs in their smug "we solved peeker's advantage!" engineering blog posts that are really just barely-disguised monorail Gish gallop.
  - efilife 3mo ago
    Yup, I just reread the post you are talking about (https://www.riotgames.com/en/news/peeking-valorants-netcode https://www.riotgames.com/en/news/peeking-valorants-netcode) and it really seems like just endless fluff and no real solutions. Reading this post is almost unbearable and it all just comes down to this part: > We built Riot Direct, our own internet backbone, to minimize network routing delays and processing time across the internet. > We’re standing up VALORANT servers around the world, ultimately aiming to deliver 35ms ping to 70% of our player base. > We optimized our servers to provide a smooth 128 server tickrate to all players. > We optimized the VALORANT game client to run at 60FPS on most machines from this decade and higher framerates for players with high refresh rate monitors. > We run clients and servers running with minimal buffering, targeting one buffered frame of movement data for clients and an average of half a frame of movement data on servers. This seems like basic stuff that every other game does.
  - tharkun__ 3mo ago
    Hah, this reminds me of my "ancient past". This must have been CS 1.4 or 1.5 times. I had terrible internet. 36k modem times, super high (ish - 150+ms at the very least, been a while, don't quote me, maybe it was way higher even?) ping to a server that had all the custom maps I loved. I got accused of cheating. I didn't. Simply a result of CS/HL netcode. I was able to "run circles" around others. Something in that version favored my local client view of things I suppose. I literally just went around corners and if there was an enemy I circled them while driving bullets into them w/ my P90. They died without even really seeing me (from what they were saying). On my end everything looked smooth and normal. This tactic never worked all that well on servers where I had the usual <120ms ping. I guess never mind at <15ms :)

xeonmc 3mo ago

> Does it cause pop-in when peeking? The goal is early reveal, not exact last-millisecond reveal. CS2FOW predicts using movement and ping, reveals enemies slightly before exact visibility, and keeps revealed enemies visible briefly. This intentionally leaks a small near-corner window to avoid late pop-in. This fails to address the main point of the "pop-in" issue relevant to fog of war systems, which is that it is the victim of the peek that gets the worst pop-in effect, the peeker much less so. The aggressive peeker gets the benefit of the early-prediction from the server since they're the initiator of the movement, whereas the victim only begins to receive the information after the peeker has already gotten two network roundtrips worth of early prediction.

webstrand 3mo ago
Interesting, could it be mitigated by the server doing its own prediction and defogging the peeker early? Or is lag prediction in CS2 not entirely client-sided.
- xeonmc 3mo ago
  It's more that momentum-based defogging means that the peeker has control over how to manipulate the server's prediction, whereas the victim who is already disadvantaged by network latency now gets an additional penalty of the movement initiation being not telegraphed. To solve this, the fog of war would need to use purely positional near-edge tolerances, which defeats the entire purpose of fog of war to begin with, which is the pre-aiming reaction time advantage of tracking the peeker through walls in addition to having a farther lever point from the cover than the peeker.
bakies 3mo ago
Why wouldn't you just send the positions to both clients in the same tick? Seems trivial to solve.
- dvt 3mo ago
  "Same tick" is a misnomer for a few reasons. First of all, games use UDP, which is basically a "fire and forget" protocol (which means packets get dropped routinely). Second of all, realtime games use some interpolation/prediction to make up for latency (and aforementioned dropped packets). So it's sort of a "relativistic" temporal system, not a linear "oh now you're at t=1, now you're at t=2" kind of timeline. And there's all kinds of complicated ways you create concensus between multiple clients, between server and clients, etc. (A lot of this remains an active research area.)

szmarczak 3mo ago

This is good. However, it still sends info about the players ~200ms ahead which still makes you lose.

Unkn0wn-d 3mo ago

[dead]

nyeah 3mo ago

Wallhack is locked into the DNA of CS for some reason. The most common defense by far is mass denial. For the great majority of players that seems to be good enough.

frollogaston 3mo ago
I'm fine as long as the game is somewhat evenly matched, and not fine if it's not. With or without cheating. Then whatever cheaters they can catch and shadowban, great. Smurfing is a way bigger problem anyway, cause some people treat the game like a job and will beat you more reliably than cheaters.
ultimafan 3mo ago
Not just CS, I don't think people realize how prevalent cheating is in any multiplayer game. The issue is compounded by the fact that many high skill ceiling games are plagued by "micro cheats" being used by players that are already fairly decent at the game even without them, making it borderline impossible for casual players to tell if what just happened to them was a fair skill gap or someone cheating. I don't play multiplayer games anymore for that reason. Too easy to go on an emotional tilt where you feel like you're suffering from paranoia and suspecting too many players of cheating. It's absolutely ruined competitive games for me.
toilet 3mo ago
Get good

lousken 3mo ago

Why hasn't valve poured a billion or two on fixing this concept and implementing it?

charcircuit 3mo ago
>Release Notes for 5/26/2015 >– Added trace-based visibility checks to prevent networking invisible enemy players. https://blog.counter-strike.net/2015/05/11988 https://blog.counter-strike.net/2015/05/11988
- jamesfinlayson 3mo ago
  That's for Counter-Strike: Global Offensive - different engine.
  - charcircuit 3mo ago
    They are forks of the same engine. Presumably this was ported as part of the CS2 update to CSGO.
    - jamesfinlayson 3mo ago
      Not sure - one of the other comments said it wasn't because Source uses BSP and Source 2 uses meshes.

Xeoncross 3mo ago

Moving away from the technical solution space - I'm curious, have their been any games (or communities) with a high entry fee/deposit (e.g. $500 USD) to join kept in escrow and lost in the event you're discovered to be cheating? There are plenty more questions like paying for mods/review, securing the money, paying for servers, etc.. but my basic question is if cost of entry exceeds cost of reward from cheating has ever been attempted in a game. Apparently buying a new copy of a $10-20 game isn't enough to keep people away from cheats. Less so when there is prize money on the line or skins (e.g. CS2) worth $100k.

lachiflippi 3mo ago
>e.g. $500 USD I've seen private cheats for games with less-than-terrible anticheats charge that monthly, if not weekly. You're underestimating how much people are willing to pay to play with cheats, and overestimating how much regular people are willing to pay to play against players without them.
- frollogaston 3mo ago
  Yeah you'll deter legit players with the escrow way before you'll deter cheaters. It's a good thought but probably not going to work.
frollogaston 3mo ago
Csgo became free at some point, and I remember the amount of smurfing increasing a lot then. Have rarely noticed cheaters, but smurfs are just as bad if not worse. They do at least require new accounts to waste some time playing deathmatch to be eligible for competitive.

MatheusFelipe 3mo ago

Why doesn't Valve implement this natively?

cedws 3mo ago
I think there’s a good possibility that they’re intentionally not fixing it, cheaters blatantly using wall hack are easy to root out and ban.

dabber21 3mo ago

I wonder if it could spawn "ghost players" in places no player could be to detect reaction

bob1029 3mo ago
Honeypot & statistics are a much more interesting avenue of anti-cheat to me. The most egregious cheaters tend to get banned the most quickly with these techniques (e.g. a 200-1 K/D ratio = a lot of samples per unit time). When it comes to cheating in video games, I subscribe more to the Dune philosophy than the LOTR philosophy. The ends (experience) definitely justify the means. Making sure that all cheaters are punished ~equally regardless of the effect of their infractions is fantastic in principle, but I'd rather if we could simply remove the ones that are obviously & openly ruining the experience. False positives suck, but there is no reason to pander to the .01% performers if you are trying to keep a multiplayer game community alive. Esports has demonstrated this is a terrible approach. We had community servers that would ban people simply for being too good before all the matchmaking stuff started up. The anti-cheat was vibes based and arguably superior to anything going on today. It wasn't "fair", but it was generally a much better experience as a player.
skimdesk 3mo ago
There was research on this published by Activision [1]. Spawning fake enemies behind the users back, inside walls, etc. The players who react to fake enemies self-identify as cheaters. [1]: https://www.activision.com/cdn/research/hallucinations https://www.activision.com/cdn/research/hallucinations

aucisson_masque 3mo ago

To me, the best anti cheat are the one you put in the game design. There is only one 'fps' I play, it's called holdfast and is about Napoleonic warfare. Muskets are so inaccurate that having a wallhack or an aimbot would be complete nonsense. There are still people who cheat in other way, but it's extremely limited. Cheaters killed 90% of the multiplayer game to me.