In Megamind: Ultimate Showdown the story begins after the movie ends with Megamind being the new hero of Metro City. A sudden crime wave hits the city, orchestrated by an organization called the Doom Syndicate. The Doom Syndicate have broken into Megamind's secret lair and obtained samples of Megamind's and Metro Man's DNA along with Megamind's DNA tracking device. It's up to Megamind to hunt down the Doom Syndicate, stop the crime wave and find the missing pieces of the DNA Tracker to locate and battle against Blue Tighten.
In Megamind: Mega Team Unite, Tighten is a good guy (assuming he has seen the error of his ways since the movie story) and joins Megamind, Minion and Metro Man to battle against the Doom Syndicate. They battle Destruction Worker and track down other Doom Syndicate members to defeat them as well. Their adventure is broadcast "live on the scene" by Roxanne Richie, who follows them and gives them helpful hints.
Megamind the video games are based on the DreamWorks_Animation animated movie of the same name. Several licensed video game tie-ins published by THQ were released on November 2, 2010 to coincide with the film's release. The Xbox 360 and PlayStation 3 version is titled Megamind: Ultimate Showdown, while the Wii version is titled Megamind: Mega Team Unite and the PlayStation Portable and Nintendo DS versions are both titled Megamind: The Blue Defender. All versions of the game have been rated E10+ for fantasy violence by the ESRB and published by THQ.
Source: Wikipedia, "http://en.wikipedia.org/wiki/Megamind_(video_game)," available under the CC-BY-SA License.