Valve are releasing new DLC section for their popular co-op zombie game this Thursday on PC and Xbox 360.

The Passing will be available as a free add-on for those with a PC or will set you back 560 Microsoft Points if you’re an Xbox 360 owner.

The developer has also announced that they’ll be bringing a new mode named “Mutations”, which will change its rules every week. This will feature modes such as “Realism Versus” and “Chainsaw Massacre”.

These game modes will not be available without downloading “The Passing”.

The game is set just after the first chapter of L4D2, Dead Centre, and has the L4D1 players meeting those from L4D2 in Georgia.

There’ll be a new co-op challenge mode in the DLC, players in the zombie team will be getting bots, a new uncommon common zombie will feature and new weapons such as the golf club and an M-60.

Apparently there’ll be new DLC for L4D1 very soon too, which will detail exactly what happens after the original events to lead to he crossover of survivors.

Have a look at our Left 4 Dead 2 game hub for more on the game.