The windows downloaded version of this game has a puzzle that softlocks the game. On the puzzle where the signs just say "Everything" and has one that says it in reverse, all the interact-able switches in every conceivable combination refuse to open a gated door. I do not know if this is an intentional Dev canon death, or game broken, but this prevents any progression.
Viewing post in Drain Mansion - Free Version comments
I am fully convinced that once players get to the "Everything room", that's just where the game ends, or the developer abandoned the project all together. Kind of a shame too, thought V1.4.0c was meant to mean that the game was fully finished, and it seemed like there was still some stuff to open. However, seeing as this is the "Full Public Build", guess the "Everything" room is just where the game ends, no ending, just a game over screen. That is to be expected from indie developers making free games though.