[mahoro]

Normally you would write a program that is a game of Doom when you run it (you create a program, then compile it and run). Dmitri created a program that does nothing and he don't even run it. But while it's compiling, it does a lot of tricky things to make typescript compiler to run Doom as a side effect.

It's extremely hacky because Typescript is not even a runtime, it's not meant to run any code at all. Typescript is a thing that takes .ts file and produces .js file (which you then run using different program - a javascript runtime).