: If you want to play with friends, you can install the Mafia 2 Multiplayer (M2-MP) mod by following guides on the Steam Community.
: You can buy the Director's Cut (which includes the classic version and DLCs) on GOG.com for a version that doesn't require a client like Steam to run.
: If you have a physical copy, you can activate the CD key by going to the Games menu in Steam and selecting Activate a Product on Steam . Essential Modern Fixes
: This massive community mod restores cut content, including missions, locations, and gameplay mechanics. It is available on Nexus Mods .