Recs.
Updated
Portal 2 is a first person puzzle game from Valve that costs $19.99. It features a single player and co-op campaign with mind bending puzzles.
SpecsUpdate
Pros
Pro Witty and funny character driven story
Four major characters drive the single player campaign and they are amazing. Three of which have explosive personalities, bring humor, suspense, sadness, and empathy, the other being Chell who doesn’t speak but her interactions with the rest of the cast make her all the more mysterious and interesting. Most of the time you don’t even see or directly interact with the characters but that just shows how great they are.
Pro Fun with portals and goop!
Expanding on the awesome gameplay of portals from the first game Valve went above and beyond with Portal 2. Bringing in great mechanics with colored goop to solve puzzles with extreme speed and bouncy jumps makes your time at Aperture Science more thoughtful and kinematic.
Pro Hundreds of hours of user-generated content
Full support to create mods to make awesome new levels, guns, or even an entirely new campaign. The game has more than 60,000 co-op puzzles created by users through the Steam Workshop and through mods. Because it is user-generated content, the quality and size of these puzzles vary widely, including everything from simple, one-off chambers to full-fledged expansions with high-quality stories, voice-overs, and new gameplay elements (for example, Mel).
Pro Well implemented tools that improve teamwork
In a game that requires perfect timing and teamwork, Portal 2 features many tools to facilitate teamwork. One of the most helpful is a 3-second countdown timer that can be initiated and shown to both players to ensure you launch that portal or jump at the perfect time. In addition, there is a marker that you can place on certain objects for your teammate to see as well as a setting that shows your partner's view super-imposed on the corner of your screen.
Cons
Con Main co-op campaign is short
The co-op campaign in Portal 2 is about 4 hours long for experienced players, meaning it could be beaten in a weekend. With almost zero replayability, this makes the game feel incredibly short. Luckily, hundreds of hours worth of user-generated content is available.
Con Steep co-op learning curve
Although the single-player campaign features a gradual learning curve, co-op gives no mercy. The puzzles start off hard and only get harder. It is highly recommended that you play through single-player first if you are not familiar with Portal's mechanics.