Portal (2007)

The 2007 game teaches a strange spatial rule by removing distractions. Early chambers let you walk through existing portals before asking you to place them, and later puzzles combine ideas you have already practised. A button, cube or portal surface has a clear job before the room becomes more elaborate. It is a strong choice for seeing how a puzzle can check understanding. Looking and moving in first person can still be a separate hurdle for a complete newcomer.