5 ms·
Show HN: Watch a neural net learn to play Snake
In browser PPO training demo, made possible by tinygrad: TinyJit -> WebGPU kernels.
Requires WebGPU.
- neduma 5mo agoMore details and implementation notes please?
- cshimmin 5mo agoIt's on the page, if you click the little info icon in the upper-right. Here's the text but there's some nice graphics there too: Snake Game, training entirely in the browser. Built on tinygrad: the rollout / targets / train graphs are TinyJits authored in Python, then compiled once to WGSL and replayed here under WebGPU. Observation: flat 10×10 board (100) + 4-dim prev-action one-hot = 104 dims. fc_pi.weight is zero-init so the opening policy is uniform over the legal actions; fc_v uses tinygrad's default Kaiming init. Per rollout: T=24 × N=384 parallel snakes (9,216 transitions), then K=3 epochs × 4 mini-batches of PPO updates. GAE γ=0.99, λ=0.95; AdamW wd=0.01; ratio clip ε=0.1; grad-norm 0.5; Huber value β=1, val_coef=1; entropy bonus 0.008333333333333333. Action mask + value clip + KL early stop. The 4-dim prev_a obs tail lets fc_pi zero the U-turn logit (the env silently overrides same-axis reversals anyway). Value loss is max(huber(v_new−td), huber(v_clip−td)) at ε=0.2. Approx-KL is sampled after each epoch and breaks the loop at 1.5·kl_target.
- simedw 5mo agoCool project! I noticed that if you go from training to watch and then back, the training temporarily drop significantly in score.
- bguberfain 5mo agoIt seems to be something related the moving average calculation. So it is just a glitch on the chart.
- deleted 5mo ago[deleted]
- beardsciences 5mo agoMy average eventually made it to about 3900, and then stagnated between 3600-3900. I'm curious if this is universal behavior or not. I'm up to about 5k steps.
- th1nhng0 5mo agocool project
- austinthetaco 5mo agomy training on a 10x10 just randomly broke. i got to like 3600 then the graph went flat, the viewer on the left just showed it constantly restarting the game, and the scores in the negative. my average is now -10.
- ldoughty 5mo agoReally cool! But right as it was nearing 4,000, it seems to have corrupted itself and no longer got any scores above 0. Not sure if that's a code bug or a neural net issue. avg500 -4.6 last 500 episodes peak 3959.3 best window roll/s 20.68 20-step avg progress 4388 562749 episodes
- r3trohack3r 5mo agoI think I noticed it reach “end game.” The snake reaches a point where, if it gets any longer, it is out of squares and hits its own tail. So it finds the route through the squares that it can infinitely loop, never eats the ball, and score starts dropping and goes negative.
- deleted 5mo ago[deleted]
- deleted 5mo ago[deleted]
- c1b 5mo agoYes it just collapses eventually — never stabilizes. The training process is flawed, I suspect it has to do with the fact that some weights blow up over time, you can see in “weights” tab. But at around 4K avg score you should see it solve the env almost every time. Just a demo :) optimized for speed over stability. Reward structure: Step: -1 Dot: +100 Win: +1000 so ~4k is max theoretical score on 6x6.
- ticulatedspline 5mo agomaybe because it doesn't understand "done"? perfect play is impossible, random variance will cause scores to drop even if the model plays well and "wins". feels like it would get stuck in a loop trying to improve what can't be improved.
- fc417fc802 5mo agoThe optimizer doesn't need to understand anything it's just an iterated mathematical construct. The author simply didn't bother to implement the necessary details to ensure numerical stability. Alternatively it might be a problem with the scoring model in the end game.
- jmclnx 5mo ago> WebGPU not available in this browser Looks like this is for Linux and Windows, on NetBSD I get this issue :(
- redshiftza 5mo agoIf you are using brave (which i assume also applies to chrome) , there is a menu at brave://flags , you can enable unsafe web GPU from there
- NoboruWataya 5mo agoI got this in Firefox on Linux, just had to enable WebGPU in about:config (`dom.webgpu.enabled` = true).
- jmclnx 5mo agoDid not know that existed, I enabled it but no luck. Must be a NetBSD thing based upon this new message: > WebGPU is not yet available in Release or late Beta builds.
- LowLevelKernel 5mo agoLink to repo?
- bozhark 5mo agoCrashed
- snats 5mo agodid a pretty similar thing last month for the text rendering library last month. trained and made a viz for the model and then made it displace text. should probably do a proper write-up:https://x.com/i/status/2038367016969724259 https://x.com/i/status/2038367016969724259
- jesuo 5mo agoGive the neural network the sense of sight, to know where the point is located.
- mavdol04 5mo agoThat's cool, i did exactly the same few years ago
- ziofill 5mo agoI noticed snake gets penalized for not getting to the apple early, is that what you really want? Snake is about how long it gets not about the balance between length and wall clock time
- foo12bar 5mo agoBut if not the snake could go into an infinite loop, never growing, never eating.
- ziofill 5mo agoWhy? It should get the reward for getting longer, but not for getting longer quicker
- foo12bar 5mo agoBecause the sessions would last forever. Think of a 1 or 2 length snake, figuring out that left down up right over and over again doesn't lose any points. You're now trapped in a local minimum. You need to make the AI get impatient (lose points) or it'll never learn.
- ziofill 5mo agoI see what you are saying but then wouldn’t it miss out on the best strategies, which do require patience and not going straight for the apple?
- jesuo 5mo agoPoorly programmed, it doesn't learn from its mistakes, the games get stuck in a loop because the snake doesn't capture a piece but the piece remains and there's a gap, constantly moving the snake along the same path with negative scores in an infinite loop leaving an unaltered yin and yang ;) there's a repetitive pattern in these infinite games between the position of the gap and the piece
- spectre9 5mo agoDid you let it train? This doesn’t happen for me
- joshka 5mo agoA previous similar idea running as a Ratatui based TUI: https://github.com/bones-ai/rust-snake-ai-ratatui https://github.com/bones-ai/rust-snake-ai-ratatui
- insane_dreamer 5mo agosound cool; would like to show my kid for education; doesn't work on Mac/Safari though (no webGPU)
- c1b 5mo agoYou can enable it in settings; works on my older iPhone.
- anthonycoslett 5mo agoMesmerizing - could be its own digital art showcase XD Love what you've done here, friend. Looking forward to what you do next. <3
- starshadowx2 5mo agoFYI this website sets off a bunch of Bitdefender alerts as being a suspicious web page. I assume probably false positives or something but still something you might want to look into. "The page https://ppo.gradexp.xyz/ https://ppo.gradexp.xyz/ has been detected with suspicious activity. It is not recommended to continue browsing this website." Same for: https://ppo.gradexp.xyz/version.js https://ppo.gradexp.xyz/version.js https://ppo.gradexp.xyz/dist/sizes.js https://ppo.gradexp.xyz/dist/sizes.js https://ppo.gradexp.xyz/dist/size_6/manifest.j https://ppo.gradexp.xyz/dist/size_6/manifest.j https://ppo.gradexp.xyz/dist/size_6/weights.safetens https://ppo.gradexp.xyz/dist/size_6/weights.safetens https://ppo.gradexp.xyz/dist/sokol/demo.wa https://ppo.gradexp.xyz/dist/sokol/demo.wa
- deleted 5mo ago[deleted]
- lucrbvi 5mo agoit's using webgpu kernels, probably a false positive
- jesuo 5mo agohttps://www.virustotal.com/gui/url/1ee8e72b55c296ee92f38937d63d35abb2353ca6281f18cf501581231b001aab/detection https://www.virustotal.com/gui/url/1ee8e72b55c296ee92f38937d... Bitdefender here shows clean
- modinfo 5mo agoWill be open-sourced?
- Ozzie-D 5mo ago[flagged]
- ionwake 5mo agodamn this was really interesting and really well executed
- dennisy 5mo agoVery cool! Not GitHub repo?
- coder0x 5mo ago[dead]
- Mariajaved906 5mo agoThis is seriously impressive. Running PPO training directly in the browser through WebGPU feels like a glimpse into where lightweight AI experimentation is headed.
- NexiunDev 5mo ago[dead]
- RyanJohn 5mo ago[dead]
- GistNoesis 5mo agoHere is how my LLM play snake : https://news.ycombinator.com/item?id=48167846 https://news.ycombinator.com/item?id=48167846
- jasonli0226 5mo agoAny plans to open-source the repo?