> > Any reason we can't make them sort of mergable? > > IF for example they are the same except for damage (ie, they are moving the > same direction, have the same distance to still move, and so on), merge them > have the damage additive? Would that work? (I guess the better question is - > does anyone see any terrible side effects with that?) I don't see merging them as very straightforward. You see, each fireball is going to be in a different stage of development. Limiting the objects per space seems a pretty bad idea to me as well: too high a cost. How about this: 1) Only make certain types of objects "hittable". 2) Sort the stack: a) floor b) items c) monsters + players d) non-hittable stuff 3) Stop "hit_map" at d) Well, it seems like you proposed something like this below, but I think this would work. PeterM