Starting out as a cleaner makes the whole situation strangely believable: there is no heroic equipment, no grand plan, just a list of chores that keeps becoming more sinister. The pressure comes from deciding what deserves your time before the clock catches up with you. Even a seemingly harmless task can turn out to be the wrong thing to focus on.
The story is short enough to finish in an evening, yet the branching outcomes give the ending some staying power. The puzzles reward paying attention, while the lonely pixel-art setting does most of the atmospheric heavy lifting. Full version unlocked, with the complete story, endings, and achievement set available from the start.