I was wondering if anyone had any suggestions on how I might create platform behavior "from scratch." That is, with events instead of by just adding the platform behavior to the sprite.

The reason I want to do this is that I would like to be able to fine-tune it to a greater degree (such as changing the direction of gravity mid-game, applying momentum from running to a jump, double-jumping, making a jump higher if you hold the button, etc.).

Oh, I forgot to say this: I'm trying to make this compatible with an xbox controller, because I and a few other people I know like to play arcade-style games on PC with gamepads made for xbox. Since that only has the one condition (control is down), it seems like I might be in for quite a challenge.