I actually designed and built a (modern?) game like this! If you have an iPhone you can check it out. It's sort of "Portal meets Doom" https://blog.sb1.io/gatee

I actually designed and built a (modern?) game like this! If you have an iPhone you can check it out. It's sort of "Portal meets Doom" https://blog.sb1.io/gateescape/ https://blog.sb1.io/gateescape/ I used some screenspace shaders for the controls and color blending, but the engine itself is an oldschool raycaster. Building it posed a lot of interesting problems like how to recessively render sprites through portals and things like that. I also open sourced an early prototype of the engine: https://github.com/gh123man/Portal-Raycaster https://github.com/gh123man/Portal-Raycaster