What happens if you remove randomness from Doom?
PRNG determinism is widely utilized in TAS (Tool-Assisted Speedrun, basically a game played using tools such as frame advance and save states to simulate a "omnipotent" player.) to manipulate games to achieve favourable outcomes. Usually the game code is reverse engineered and a Lua script is created that searches forward in the RNG outcomes to find the ones you want, it is then up to the runner to execute actions in the game that give you that state.One example of this technique which I particularly like is the "100% Souls" run of Aria of Sorrow, where the normally very grindy process of getting enemy soul drops is trivialized by making sure that every enemy will drop a soul the first time it's killed: https://www.youtube.com/watch?v=DfkJpzBoJ-M