Microsoft's online network for the Xbox 360 is in for a busy couple of weeks. In addition to Xbox Live Arcade games ranging from After Burner Climax to Tecmo Bowl: Throwback, the publisher has Halo 3 for Games on Demand and under-the-radar expansion packs for BioShock 2 and Left 4 Dead 2.

　　Sega's After Burner Climax takes off on XBLA for 800 Microsoft points ($10). The flight combat game brings with it three high-octane jets and 20 stages to burn through. It is joined on XBLA this week by Puzzle Quest studio Infinity Interactive's Puzzle Chronicles. Also clocking in at MSP 800, Puzzle Chronicles is an "active puzzle combat" game with role-playing elements.

　　After Burner Climax is just one new addition coming to Xbox Live. As previously announced, Bungie's blockbuster Halo 3 leads the Games on Demand update for this Tuesday. The top-rated sci-fi shooter carries a $29.99 price tag and should serve as a suitable primer for gamers expecting to hop into the Halo: Reach multiplayer beta on May 3. Next week's GOD additions will be Far Cry 2 and Shrek the Third, both of which go on sale April 27.

　　On April 28, Microsoft will huddle up with Tecmo Bowl: Throwback for MSP 800. Like other retro revamps, Tecmo Bowl: Throwback will include options aimed at purists, as well as those desiring a modern update. The game will let players switch from classic-style 2D graphics to new 3D visuals, customize their teams and rosters, and hit the global gridiron with an online multiplayer mode.

　　A number of high-profile titles will also get an infusion of postrelease content. On April 22, Valve will release the first add-on pack for Left 4 Dead 2 on the Xbox 360 and PC. The Passing scenario takes place just after the Dead Center campaign. It ties together Left 4 Dead 2 and its predecessor from 2008, as it sees the original game's cast meeting up with the second's contingent of survivors. It will cost MSP 560 ($7) on the 360, though the PC version will be free.

　　Next week sees the release of the Rapture Metro add-on for BioShock 2. The MSP 800 ($10) pack includes six new multiplayer maps set in the dystopian underwater city, as well as two new masks and three achievements. The add-on also raises the multiplayer rank maximum to 50. Square Enix's Just Cause 2 will also gain the Black Market Aerial Pack that week. The MSP 180 ($2.25) pack includes the F-33 DragonFly jet fighter, dual parachute thrusters, and a multilock missile launcher.

　　And for those gamers who can't be bothered with all these newfangled games, Microsoft also has a round of new additions to the Xbox Live Game Room on April 28. Vintage games slated to arrive include Super Breakout, Pitfall, Megamania, Night Stalker, Rack 'Em Up, Realsports Volleyball, and Basketball. The catalog update will mark the institution of weekly updates to the service, which had temporarily ceased following its mid-March launch.