Been working a lot on AI. What I've done is created a system that controls the physics of globally. This means I don't have to worry about scripting each NPC to walk on slopes or fall when they walk off a cliff. It's still fairly buggy, however. Some NPCs will consider a slope a wall, or will maybe miss a wall.
Also worked a lot more on NPC interaction. Turtles can be jumped on and such. I'm not entirely happy with it though. Right now I'm doing hit checks from the player's movement, which means I have to communicate to the NPC that it was hit. This means it's always going to be a frame behind, which really feels off(you'll see my player goes about half-way through the NPC before it reacts, this isn't bad detection). I might just rescript and add collision detection to the NPC's themselves, which would mean they'd act instantly, and I can alter player status(like his velocity) instantly just as well since it's all global.
Also, changed the music for now so I can introduce... DANCING TURTLES. I've scripted dancing much like enemies in New Super Mario Bros. I can easily make any NPC I want dance with the song. The reason I change songs was because the Super Mario World tune didn't really have anything in it that I thought would seem right to the turtles dancing to.