Yeah Rob's method is probably the best. This is basically how Sierra's old AGI and SCI interpreters worked. A problem with this method is that it assumes all areas are flat. Stairs etc. where you would need the y-dimension would require a different approach. Well I guess you could script that.... What I first had in mind was to create a 3d-surface and just using blitz's collision-checking to check for boundaries, that would allow height-changes too... Well I think I try both and see which one works out best.