Microsoft has announced four new titles for its Xbox LIVE Arcade service, including highly anticipated sequels and a game based on a much loved animated TV series.

First up is Geometry Wars: Retro Evolved 2 from Bizarre Creations and Activision. The game will debut next month and will include six gameplay modes, new enemies and a diverse list of new Achievements. The game will also sport multiplayer support for up to four players (vs and co-op) and razor sharp 1080p visuals.

Next up is Galaga Legions from Namco Bandai Games, bringing the legendary game into the 21st century with new gameplay mechanics, updated visuals and waves of ferocious enemies. The game is created by the same team that developed Pac-Man Championship Edition for XBLA. Microsoft says this too will be out next month.

Also coming in 2008 is Portal: Still Alive from Valve. The XBLA version features the full Portal single-player game that has already been released for Xbox 360 as part of the Orange Box, plus a new Challenge mode.

Arriving in 2009 is a new South Park game from South Park Digital Studios/Doublesix/Microsoft. The game is based on the Emmy award winning show and is coming exclusively to the XBLA platform. Game specifics and the title are still to be announced.

For the latest news, screens, videos and previews from E3 2008 head over to the E3 Blog.