You should be able to do it by changing the logic around. In it able to open the capx right now so this may be a bit different. You don't even need a variable. You could take a loop over all the tiles and make these sub-events to keep for example tiles 4 and 6.
Or if you still wish to use a variable just structure the text variable used for the list like this. Comma seperated and starting and ending with a comma.
Global text keep=",4,6,"
Then use a sub-event like this:
System compare: find(keep, ","&tile&",") = -1
Thanks! Here's a screencap of what I have so far, it WORKS, it's just going to be inefficient when I fill up those tiles:
I'll try and use your suggestion, I'm not sure if the screengrab is of any use to you. I have three tilemaps, one for display, one for solids and one for jump-thrus.