4 ms·

It's fully deterministic, multiplayer works by only sending user input around (at a reduced tick rate) and the unit movements get calculated locally from that.

TacticalCoder 4y ago
> It's fully deterministic, multiplayer works by only sending user input around (at a reduced tick rate) and the unit movements get calculated locally from that. That's interesting. I wonder why the other poster say the replay functionality would turn into nonsense at some point. Now if the game is deterministic and multiplayer works by only sending user inputs around, why the save / continue feature wasn't implemented that way? In any case I love to read about how these games worked!
- Macha 4y ago
  Multiplayer requires all users are on the same version. SC2 replays also require this. SC1 may not have. Determinism would only have applied if the version used for playback was the same as that used for recording.
- celdon25 4y ago
  The replays can possibly malfunction if you speed the playback up faster than 1x. Not sure about the technical reasons, but the devs never fixed it. Many players still don’t know about the workaround to use 1x though.
- Linosaurus 4y ago
  > Now if the game is deterministic and multiplayer works by only sending user inputs around, why the save / continue feature wasn't implemented that way? Your only interpreter for the data is the entire game engine. By design it's going to use most of the power of the target hardware, so cannot run faster. Ie, 30 minute load time if you had played 30 min.
  - Jare 4y ago
    Running the simulation is not going to use most of the power of your machine, in any remotely sane design: - a huge part is going to go to rendering, which you don't need to do if you only care about the end state - in many games, the simulation runs at a much lower frame rate than the game, so perhaps you see the game animated at a silky smooth 60 fps but internally the sim runs at a fraction. 10 and 5 fps for the sim are common. - some sim architectures may allow you to run the sim at a variable frame rate and still generate deterministic results. So (ideally) you tell the sim to run a single step of 30 mins and you get the end result. In practice of course variable steps will be limited to much less, but Supercell mentioned reducing their server sim cpu costs by 80-90% with this kind of trick. All added up with reasonable guesses for a well optimized case: 30 mins of sim run at 1 sim tick per second of game time, where sim ticks take say 2ms, could take 3.6 seconds to sim, not 30 minutes.
- archagon 4y ago
  I recall a Starcraft multiplayer game diverging with a dorm buddy back in college. Thought I was winning; turned out we were playing entirely different games!

TacticalCoder 4y ago

> It's fully deterministic, multiplayer works by only sending user input around (at a reduced tick rate) and the unit movements get calculated locally from that. That's interesting. I wonder why the other poster say the replay functionality would turn into nonsense at some point. Now if the game is deterministic and multiplayer works by only sending user inputs around, why the save / continue feature wasn't implemented that way? In any case I love to read about how these games worked!

Macha 4y ago
Multiplayer requires all users are on the same version. SC2 replays also require this. SC1 may not have. Determinism would only have applied if the version used for playback was the same as that used for recording.
celdon25 4y ago
The replays can possibly malfunction if you speed the playback up faster than 1x. Not sure about the technical reasons, but the devs never fixed it. Many players still don’t know about the workaround to use 1x though.
Linosaurus 4y ago
> Now if the game is deterministic and multiplayer works by only sending user inputs around, why the save / continue feature wasn't implemented that way? Your only interpreter for the data is the entire game engine. By design it's going to use most of the power of the target hardware, so cannot run faster. Ie, 30 minute load time if you had played 30 min.
- Jare 4y ago
  Running the simulation is not going to use most of the power of your machine, in any remotely sane design: - a huge part is going to go to rendering, which you don't need to do if you only care about the end state - in many games, the simulation runs at a much lower frame rate than the game, so perhaps you see the game animated at a silky smooth 60 fps but internally the sim runs at a fraction. 10 and 5 fps for the sim are common. - some sim architectures may allow you to run the sim at a variable frame rate and still generate deterministic results. So (ideally) you tell the sim to run a single step of 30 mins and you get the end result. In practice of course variable steps will be limited to much less, but Supercell mentioned reducing their server sim cpu costs by 80-90% with this kind of trick. All added up with reasonable guesses for a well optimized case: 30 mins of sim run at 1 sim tick per second of game time, where sim ticks take say 2ms, could take 3.6 seconds to sim, not 30 minutes.
archagon 4y ago
I recall a Starcraft multiplayer game diverging with a dorm buddy back in college. Thought I was winning; turned out we were playing entirely different games!