I've never heard of it. Is it a shoot em up game?
Yep, one of the finest ever conceived. Mafia was one of the first games to feature a well-developed storyline and multiple ways to do things. In the most important missions, you can choose who lives and who dies. The characters are top notch and the action is great. You get to use lots of very authentic weapons, which all feature great sound effects and the physics of the game allow you to kill enemies in a variety of very satisfying ways.
What sets Mafia apart from the rest though, is its graphics engine. The folks at Illusion Softworks outdid themselves. They created a believable environment that was ahead of its time. Now, with modern tech, Mafia would be the most immersive experience, especially if Tommy, (the main character) was allowed to go in and out of his home like the ones in GTA V do. That would blow my mind for sure.