I made a maze world a long time ago to demonstrate collisions with a bunch of walls that are all in a list. It just checks to see if the person is touching anything in the list and it pushes it back if it is. The problem is though that it only works if you put up walls, rectangles. You would have to tweak it to make it work with other objects, but it works fine if you just put a bunch of walls around the objects where you don't want it to pass through.
Thread is here
Check out my best projects so far and please comment:
Tic-Tac-Toe 2.0 ................... http://www.alice.org/community/showthread.php?t=3548
Alice Paint ........................... http://www.alice.org/community/showthread.php?p=23408
Real-Time Clock .................. http://www.alice.org/community/showthread.php?p=12725
Maze Game ......................... http://www.alice.org/community/showthread.php?t=4301