From a recording to an understanding
Watch the AI is the mode where the game plays itself on a loop, for streaming. Until this week it followed recorded test scripts. It walked where a player would run, rarely used the double jump, teleported back onto its script when it drifted, and stalled for minutes at the first boss. The morning's run showed it: 1-1 and 1-2 cleared with teleport assists, then 1-3 stalled at Bruiser until the stage clock ran out at 300 seconds.
The stall came down to one small bug. The script waited for "stagger" in the boss's pose name, and the first pose with that word in it is the moment before he can be stomped, so every stomp came a third of a second early.
The fix was bigger than the bug. The script follower is replaced by an AI that plays from its own understanding of each stage.
- A map of every stage. At the start of a stage it reads the level's collision and works out every spot Mittens can stand on. It then simulates his runs, jumps, double jumps, drop-throughs and falls using the game's own movement numbers, so it never plans a jump he cannot make.
- It plays like a player. It takes a run-up when a jump needs one and corrects every jump in mid-air. It uses the double jump to save a jump that is falling short. It swims, surfacing for air before it runs out, takes warp boxes, shoots through crate walls and stomps or shoots enemies in its path.
- It knows where things are. Each of the 24 stages has a guide, written from the level files, listing the objectives in order, every secret and how to reach it, and every warp box. It takes detours for secrets when they are worth the time.
- It explains itself. A plan panel ticks off objectives and counts secrets found, gold markers point at secrets, a dotted trail shows where it is heading, and a commentary line says what it is doing ("Detour for the secret: hop-shoot the top crate").
Fighting bosses with normal inputs
Three bosses now have new fight logic that uses only the inputs a player has. Against Bruiser it fights from the top of the washing machine, where almost nothing reaches it, makes him dizzy with well-spaced hairballs and stomps him; it holds jump so the bounce lands a second stomp as he gets up. Against Snookums it waits on the mower so it leaves no scent trail, blinds him with a level shot when his nose goes down, and stomps. Against Skip it hops onto his back the moment he plants. The other six fights are arena puzzles and still use their proven scripts.
What was measured
In early runs of 1-3 in the editor the new AI found the two underwater secrets by 0:23; the old way took 1:18. Those runs also showed three problems: a run-up that looped back and forth, one drowning under a ceiling in the pool, and losing track of where it stood while riding. All three are fixed in code but not yet tested in a run, and none of the new boss fighters has fought a full fight yet. The AI is now tested through its own log: each stage writes one line with objectives, secrets and pickups found, jumps missed, where it fell back to a script, and how each boss fight ended.