Up is based on the animated movie of the same name. Carl Fredericksen always wanted to be an adventurer but he never got around to it. After his wife dies he gets depressed but finally decides to experience adventures after all. He gets accompanied by the scout Russel.
Most levels are played with two characters with different abilities: Carl can use his walking aid as jumping help and crowbar while Russel balances on small ledges, catches insects or blinds enemies with his magnifying glass. Sometimes the dog Dug joins them who can pass through small holes and swim. The levels are basic platforming stages with many puzzles which need all these abilities to be solved. Of course this can be played in co-op too. Diversion is brought by a few flying levels with a biplane.
There are numerous differences to the Xbox 360/Playstation 3/Wii version. There are more levels, additional mini games like a raft trip where the player has to dodge crocodiles, the story is told with actual cutscenes from the movie and there are more unlockable extras, e.g. cheats. The two player characters gain additional gadgets during the game which can be used to reach new areas in already beaten levels. The multiplayer modes are also different: this version lacks the simultaneous flying duels for four players but two variants for two players and six other mini games which can be player as tournament for four players.