I would be interested to know how you made this! This is a really cool mechanic. and the rest of the game is very polished. Your submission is definitly in my top 5!
Viewing post in Forward Thinking jam comments
You can get a better idea of exactly how we did it if you download our source code, but basically there is a world scene in Godot with two tilesets, one for the regular map, and one for the apocalyptic future that you see through the portals. All the portal effects are controlled by shaders, and the inside uses the texture of the apocalypse tileset, along with the collisions from the tiles. Thanks for playing!