Feel like taking Ellis, Coach, Rochelle and Nick through "No Mercy" or "Blood Harvest"? Thanks to the work of some enterprising modders, the L4D campaigns are now playable in L4D2.
Some Left 4 Dead fans have a hard time letting go of the past - despite L4D2 being an improvement on the first almost across the board, there remains a smattering of hardcore L4D1 aficionados who can't fathom the idea of a game without Zoey, Francis, Bill, and Louis - or a game with all-new campaigns. Valve is already taking care of the first group with its The Passing DLC campaign, but it's up to modders to take care of the second.
And so they have.
The "L4D on L4D2" Steam Group has been hard at work porting the first game into the second, and looks to be all but complete. The original four campaigns are now for download in two flavors - an "Original" that preserves it exactly as you remember, and a "Modified" version that adds the new melee weapons, new guns, new Infected, and the special Daytime lighting of L4D2. Oh, and it looks like all eight Survivors will be playable, as you can probably tell from the above video that swaps out Rochelle for Zoey. There won't be any customized dialogue between them, though - at least, not until The Passing, when Ellis can hit on Zoey and Francis can piss off Coach by saying he hates football.
So there you go. You can download the mod here, and now all sixteen L4D fans who haven't made the switch yet have no further excuse.