Today Codemasters released an official press release containing more info about the game, along with it came some interesting images.
The game is all about the strange city Jericho that suddenly appears is an abandoned desert. Inside the big city resides an evil ghost that has zoned Earth as its target. As a player you'll control an elite Special Forces team that has to break through the city's walls. The thing is, between every wall is another timezone/era. That way you'll travel from modern warfare to WWI, and from that to the middle ages.
The game will appear on the PC, 360 and PS3 in the autumn of 2007.