Half-Life Mobsters have released a design document that details there multiplayer gamemodes and they have released a coupple of renders of there sawn off shotgun.

Here's a snippet:

Bank Robbery

In this type of game play the user will be have the same options of either joining the Cops or the Mobsters. After re-spawning into a new round the players on the Police force will be at the police station and will be alerted of where the bank robbery is taking place.

You can read the rest of the design document here