I’d like to continue with the DLC packs.
First would be your typical map expansion pack, but since (in this case) these campaigns are shorter, it would add 2 (3 if you count survival only maps). The first campaign would take place between the aforementioned beach/pier and china-town docks. It would be a very short, 2 chapter campaign called Paradise Lost, about (as its name would imply) a tropical island. Your boat would have to stop for something stupid like gas or food, or just to get out of the rain (because this is during the large storm mentioned earlier).
Next in this map pack would be a 3 chapter campaign centered on a prison, with the first chapter being a large turnpike leading there. Many can guess how this one would work out, so I’ll go on.
Lastly with this map pack would be a campaign that’s exclusive to survival mode (like Last Stand), known as Now Slaying, It includes 2 maps. 1st being a large scale movie theater, and 2nd being a drive-in theater.
Another DLC would be one that would be cheap, but essential. It would be the “Flash-Back” pack. Not only would this add the mutation “Flashback” (I’ll explain in a moment), but it also allows you to access all the maps from the 1st two L4D games. The only catch is that in order to use maps from one of the games, you need to own that game. Meaning: Players who get this game before getting the 1st two would be inspired to get them, just to play them in L4D3, this also rewards players who have been with the series for a long time. FlashBack mode would allow you to play any map (not just from the 1st two games) with settings that match either game.
For example: Flashback 1 makes so there’s only Smokers, Hunters, and Boomers, along with period accurate items and weapons, so it feels more like your playing the original game (this is more of an incentive to the people who only own the 3rd game, allowing them to at least see how things worked in previous games).
And no, owning the Cold Stream DLC for L4D2 would not grant you the L4D1 maps, you would still need the original game. (L4D1 would also allow for Last Stand, which is still not present in L4D2)