Alien Swarm adds AI Director

Valve's free co-op shooter Alien Swarm – an updated Source version of an old Unreal Tournament mod, released last month – has had a Left 4 Dead-style AI Director added to increase the challenge and variety.

According to Valve's press release (via RPS), the new Onslaught mode "introduces an AI Director that dynamically generates swarms of aliens based on several factors, such as the squad's stress level.