Portal 2

Portal 2 is a first-person puzzle game from Valve, the sequel to the cult game about the Aperture Science laboratory. You play Chell, who wakes in a half-ruined complex where new tests await, accompanied by talkative artificial minds, GLaDOS among them.

The core is the portal gun: you create two linked portals on walls and floors and step through them to reach the exit. Each chamber adds new elements: gels that change surfaces, light bridges, lasers, platforms. The puzzles give a real sense of understanding, while the humour and dialogue make the journey fun. There is also a cooperative campaign.

According to HowLongToBeat, the story takes about 9 hours and a full run about 23. In a month at roughly 60 hours you can finish the single-player campaign with lots of room. It works offline; online co-op with another player is not part of the rental.