Move your mouse to steer. Hold Space or click/tap to boost — you'll move faster but shrink, so use it to cut off the other snake and force a crash. Eat the dots to grow — they respawn elsewhere a few seconds later. The map is 5× what you can see, and you can only see a circle around your own snake, so the rest of the map stays dark — check the minimap in the corner to see where you are. Crashing into your own tail or the arena wall is safe; only crashing into your opponent ends your run.