Strange Horticulture -You run an occult plant shop and identify plants by leafing through a botanical guidebook, matching illustrations and descriptions.

HighFleet - Intercepting enemy radio transmissions means using the in-game codebook and manual tables to decode messages and triangulate positions.

The Signal State - A Zachlike about repairing farm equipment with modular synth racks and lots of documentation.

Retro Gadgets - You build electronic gadgets from scratch, and reading the chip documentation is basically the whole game.

Sethian - You learn a dead alien language by studying an in-game dictionary/manual to converse with a computer.

Carrier Command 2 - Co-op crewing a carrier where the in-game manual is dense and necessary, giving strong Tin Can/submarine-crew vibes.

Objects in Space - Space sim, flying a submarine-like ship, reading dials and signals.

Jalopy - Roadtrip / car maintenance game set in Eastern Bloc.

Reentry - Crazy realistic space sim where you follow manuals, procedures, checklists etc to complete missions like the Apollo moon landing.