Platforms
Shrek the Third is available for all major platforms and then some: Sony Playstation and PSP; the Nintendo DS, Wii, and Game Boy Advance; and XBox 360. According to Gamespot, the XBox 360 version can also be purchased as part of the Microsoft Children's Miracle Network Games Bundle, along with Sonic the Hedgehog and Viva Pinata: Party Animals.
Where to Buy
Because the game is no longer considered a new release, retailers like Best Buy, Gamestop, EB Games, and Target no longer sell it in stores. However, Gamestop and sister store EB Games do have several versions available online, including a PC download. All games are previously owned.
As is often the case with games that have gone out of stores, Amazon is the buyer's clearest, easiest option. On Amazon, every version of the game is available for purchase, new or used.
Object
According to Gamespot, Shrek the Third is, essentially, a collection of 20 puzzles through which players guide different characters from the series. Each character has unique abilities, meaning that the gamer must swap out characters in order to accomplish certain tasks. There are 20 levels in total, but according to user reviews on Gamespot and Amazon, playtime will not last beyond 10 hours for an adult. Children will have a bit more difficulty hacking through the puzzles, but not by much, as they repeat throughout the game.
Other Titles
There are two other video games related to Shrek the Third. In Shrek's Carnival Craze Party Game, players make their way through 28 mini-games, akin to the Mario Party series. The game is available for Nintendo DS, the Wii, PC, and Playstation 2.
Shrek the Third: Ogres and Donkeys is a Nintendo DS game in which players 'baby-sit' Shrek's and Donkey's offspring. According to Amazon, the manufacturer has discontinued it. That is also the case with the PSP version of Shrek the Third.
Both games are readily available on Amazon, including that which was discontinued.