Activision Blizzard today released three major sequels for their largest gaming franchises, each likely to sell hundreds of thousands of copies and expand content for a phenomenal base of active gamers.

World of Warcraft, with over ten million subscribers and more than 60% of the MMORPG worldwide share, has opened its servers to the second expansion, entitled Wrath of the Lich King.

Wrath of the Lich King adds a host of content to the existing game world. Players will be able to explore a vast new continent, and battle other high-level heroes to determine the fate of Azeroth. This expansion has been in beta for some time now, and you can read our previous findings here.

Call of Duty: World at War, the latest addition to the extremely successful Call of Duty franchise, takes us back to the Pacific and European theatre of World War Two for some exhilarating first-person action. Developed by Treyarch and utilising the Call of Duty 4 engine, World at War provide players with an opportunity to play as U.S. Marines, German Wehrmacht, Japanese Imperial Army and Russian Red Army factions in a variety of game types. We've had a go at the multiplayer beta and early indications suggest it's going to be a hit. Stay tuned for a review shortly.

Guitar Hero: World Tour is the much-anticipated sequel to Guitar Hero III: Legends of Rock and some healthy competition for Electronic Arts' Rock Band. Guitar Hero World Tour transforms music gaming by expanding Guitar Hero’s guitar gameplay into a cooperative band experience that combines wireless instruments with new online and offline gameplay modes, including online Band Career and 8-player “Battle of the Bands,” which allows two full bands to compete head-to-head online for the first time ever. Check out our preview and interview with Red Octane's co-founder here.

It's not just Activision Blizzard who are having the busiest day of their gaming careers, Electronic Arts haven't exactly been sleeping and have decided to release the hugely anticipated Parkour-based Mirror's Edge to an adoring public. We'll bring you our findings shortly, but it seems that this new IP will be one to watch closely. We had a look back in March, and those curious to see what all the fuss is about can grab some trailers from GP Downloads.

If you're a fan of off-road racing then it's unlikely you'd have missed Sony's Motorstorm 2 Pacific Rift, also released today. We had a go with some beta code a while back, and despite a few glitches it shows real promise. There's something inherently satisfying about ramming other vehicles and smashing through foliage, although I can't imagine why. You can read our thoughts on this game here.

As if these five blockbusters weren't enough, Nintendo have released Wii Music, Ubisoft have chimed in with Petz Sport Dogz Playground, Rayman Raving Rabbids and even portable versions of Shaun White Snowboarding! Not forgetting that the Xbox 360 version of Red Alert 3 is on sale today as well.

As the busiest day in video game history draws to a close, try to spare a thought for the frantic staff at your favourite gaming retailer, the stressed and often under-appreciated distributors who have organised stock, and the couriers who are probably on ACC by now after carting around Guitar Hero World Tour bundles. Roll on the holidays!