Since you might be facing a massive amount of space, object and npc attributes, you might want to look into sparse arrays to conserve memory usage.. http://www.vb-helper.com/tut2.htm .. A task like this can easily get out of hand if you employ sloppy logic, but can also be done very efficiently with a little craftiness.. Zelda is a great example.. I love that series in 8bit Nintendo.. Funny thing is, if someone were to attempt to recreate it on a modern pc using poor technique, they may easily run out of resources.. I hope you keep posting your progress even if you don't perceive a problem because collabritive thought will almost certainly improve your efficiency