Stitch: Cosmic Slugger is a baseball Flash game released in 2009 (according to the copyright year) where players play as the alien genetic experiment Stitch (Character) in a home run derby against some of his "cousins" (i.e. Jumba's other genetic experiments). The gameplay and difficulty is identical to Winnie the Pooh's Home Run Derby!; players move Stitch around the batter's box and click to swing his bat at pitches thrown by one of the experiments. Stitch has a limited number of pitches in each level to hit a target number of home runs; if he reaches the target, then the player unlocks the next level (and thus Stitch's next opponent), but if he fails, then the player has to restart the level. Hitting home runs also earns the player points to spend on batting power and contact upgrades.
The eight opposing pitchers are as follows:
- Cannonball
- Richter
- Kixx (Character)
- Dupe (Character)
- Swirly (Character)
- Plasmoid (Character)
- Clyde
- Yin (Character)
There are several differences between this game and the more infamous Winnie the Pooh game:
- The level selection screen shows the names and heads of all eight opponents, with the heads silhouetted if the level hasn't been unlocked yet, although the level select only shows one level at a time. Pooh's level selection screen shows all the opponents at once, but only the ones who are unlocked are visible, while locked opponents are completely hidden.
- Stitch has only two upgrade stats: power and bat contact. Unlike in Pooh, movement speed is pre-set and cannot be upgraded, although the hyperactive Stitch moves around the box quickly anyway. Additionally, while power has twenty upgrade levels like in Pooh, bat contact has only three. However, upgrading this stat, which requires more upgrade points than in Pooh, changes the bat and Stitch's uniform, whereas Pooh Bear keeps his same wooden bat and iconic red shirt throughout.
- Unlike in Pooh, the player can exit a game in progress at any time, although no upgrade points will be awarded for leaving the game early.
- There are unlockable trading cards featuring images of Stitch that are unlocked after winning every two levels. There are four card designs to unlock.
- Apart from the change from Pooh characters to Lilo & Stitch characters, the setting is changed from the Hundred Acre Wood to a beach (presumably ), with the area past the outfield being the Pacific Ocean, which justifies the ball disappearing when it lands as it splashes into the water (unlike in Pooh where it vanishes into a field that does not look like it has tall grass).
In a more trivial note, Slugger (Character) (X-608) does not make an appearance despite the kind of game it is and the fact that the word "Slugger" is in the title.