There's no sign of a price for the upcoming "Gene Expansion Pack," but its contents have been laid bare for us to drool over. Included are three new maps ("City of Sorrow," "Underground Waterway" and "South American Power Station"), two new playable characters (Meryl and Johnny), each with their own special abilities, a new game mode (Survival) and a new reward system. Phew. That's a lot of content.
Playing in Survival mode allows you to earn Reward Points, which can then be spent to kit out your characters in new gear. Speaking of characters -- females enter the fray with this expansion pack and for those of you who don't have any more character slots available to make one, there's a "Gene Expansion Plus" package which includes everything mentioned above plus another character slot.