Board Thread:Questions and Answers/@comment-76.246.71.61-20140815012928/@comment-14600979-20140815013423

http://petitcomputer.wikia.com/wiki/Simple_Map_Collision_Detection_%28Array_Based%29

This didn't help? This involves stroing your map data as an array.

You can use BGCHK to look at the tiles around the player and if they are certain tiles, go back one/however many are being traveled at a time pixels when attempted to move towards.