Half-Life is a first person shooter in the same vein as Doom and Quake.  What sets Half-Life apart though, is the more detailed backrounds and more realistic gameplay.  In Quake, you blast everything to pieces and plow your way through the levels.  In Half-Life, you pretty much do the same thing except the backrounds and characters are more interactive...it almost seems like it's part role playing game. The graphics rival those seen on Quake and Unreal, and the story has more back-bone also. Overall, Half-Life provides more of a realistic environment to explore (and destroy) than most other games of it's kind.  If you can't get enough of first person shooters, Half-Life is a great choice for some more action.