We have updated the game with a new Survival mode! Now you can battle endless waves of enemies in the Survival Mode with up to four players! The lobby system has also received a needed update and now allows players to join games in progress.
[CHANGELOG 10/21/2011] Gameplay: - New Mode: [Survival Mode] Now you can duke it out for wave after wave of enemies and test your endurance either alone or in co-op matches.
Networking: - Updated: [Lobby] Now players can join a game in course. - Fixed: [Several connection issues] We have reworked the games network code which should stop the Unable to Connect issues.