Even though Left 4 Dead 2 contains the entirety of Left 4 Dead 1's campaign levels, complete with all the bells and whistles the sequel brought with it, there's still a case to be made for playing through the original Left 4 Dead as the devs originally intended — no melee weapons, fewer fourth wall breaks, and no grenade launchers.

Also you shouldn't be buying either game on their own. Buy the Valve Complete Pack on sale for like $10