Something I'm sure I've seen in other's levels is having a room on one map square (say x1000 y1000 for example), then when they walk off the right hand side, you appear in a square 5 to the right instead. How is this done? I've looked at other's levels in the editor and can't see any shifts, and checked the properties.

I ask, because I'm new to the editor and basically want a section where you make some simple jumps in a cave, reach the next screen to grab a powerup, then head back. When you return to the first screen (the one with the jumps), I want a few enemies to have appeared in there - so presumable I'd need 2 versions of the screen, one with enemies and one without, so if the screen is approached from the left it does not have enemies, but if from the right you get the one WITH enemies (and even better, if possible, once you've got the powerup, you ALWAYS get the one with enemies, no matter which side you enter from).

I've seen this done, but can't work out how....

Also, how do you do the 'walk off right side of screen, appear on left of same screen' trick?

Thanks guys