A while ago as practice for fun I had a go at recreating mario, the physics still arn't perfect, but I think I got them pretty close. Was fun programming an old classic. This is a good way to practice making platformers smooth and seeing how mario did it. Play and/or download the engine below.
Click below to play the engine. Arrow keys to move.
Click below to download the flash file
It's in Actionscript 2.
Hopefully this helps with making your platformers smoother. All graphics are mario owned of course. Also testing this new posting and it's pretty cool editing on the fly instead of going back and forth correcting mistakes.