Hello and welcome back ^^
finaly a chance to share my stuff

*cough*
i also work on a 2d platformer, super mario stile.
i always hated collision detection because i could always find how to detect collision, but not what to do after collision happened. i didn't like to have seperate ground tiles that move the player up, or wall tiles, that move the player sideways. how to detect if the player is on the left or right side of a wall?
well i wrote this. it only uses the lock pixels command and the dot command for display (no sprites) and checks collision in small lines left, right, above and under the player.
here is the code:
EDIT: noooooooo my code seems to be too long, the site doesn't seem to like it. i will upload it on my homepage and post a link
EDIT2:
http://www.crassegames.com/jumpnruntest.txt
please tell me if this runs at a reasonable speed. i can only test this on my gaming/3d rendering machine. some may have less CPU power and i would like to know it my code even works on anything than my machine.
and if anyone is interested, here is a little tool that i made (it's not finished, but it works for now). you can create simple images, output it as data statements and use it inside of dbpro itself
i used it in the above project for my... almost not as bad as the worst character images i've ever created. but it works and i'm not a pixel artist
http://www.crassegames.com/littlepainter.txt