Free roam games in a prison would be highly praised, even if they were dumb Pokémon roms or really old GTA releases.

Or just give them long gamebooks -not necesarily fantasy themed- a la CYOA but with pencils and erasers (and, yes, they can be turned into a weapon, but inmates will use for paperwork or prison classes anyway).

Some of them allow you to roam under a whole city and solve enigmas/puzzles and fight.