Some things are still random even when you control the RNG seed in every room.
Whether and how much money will drop from an enemy is rolled during combat, without any RNG resets.
Initial enemy spawn locations are rolled with fixed RNG uses every time - they happen before Zagreus can take any actions to affect RNG. This ensures that same position in the spawn point list (MapState.SpawnPoints) is used every time (eg. the 4th entry). The spawn points are loaded into this table in an arbitrary order by GetIds (Combat.lua#3879), so different spawn points will be in the selected position from run to run.
Subsequent enemy spawn locations are rolled during combat, without any RNG resets. Which spawn points are eligible also varies depending on Zagreus’s position.
Which enemy will spawn is rolled during combat, without any RNG resets. The enemy set for each room is fixed for the route.
Enemy movement and attacks are rolled during combat, without any RNG resets. They also depend on Zagreus’s and the enemy’s position.
Gemstone room rewards have an on-pickup voice line. This is rolled before RNG resets at the end of the room, based on the combat RNG.
When a Price of Midas appears in a well, two rolls occur:
The Price of Midas will take one of two possible values based on this order.
Boons appear in an arbitrary order in the sell well.