The thing about pixel perfect collision detection is that it is so CPU intensive. If you were to check every object against every other object you would have an unplayable game. What I would suggest, and this is a common way of doing things, is to use bounding boxes for possible collision and when two bounding boxes overlap, use pixel perfect collision detection for the two colliding objects. That way, you will not need nearly as much processing but have pixel perfect collision detection. As for how to implement it, checkout Travellers' site. Otherwise let us know (me tired, must go bed now). As a sidenote, when you do do the pixelperfect bit, you may want to have a two dimensional array with the pixel masks preloaded into these, just another way of improving performance. There is another post regarding this on the forums so have a look around, sorry I don't know where it is.