If TF2 Had A Singleplayer Campaign...

I actually did think about this a while back, and actually built a prototype for the concept to get it setup.

A lot of the attempts at this concept are either extremely gimmicky or require you play one specific class. The idea that I had was pretty simple: You can choose from any class, resupply rooms function as checkpoints, and you have to accomplish a few objectives that are no different from multiplayer TF2, such as capturing/defending control points, moving payloads, etc. Potentially some stages would be just you going from point A to point B. Nothing fancy, just straight play the game against bots throughout a journey across the badlands.

I don't think tf2 would fit a single player story mode, I feel like the story is the comics it self and the game play in the maps are just a reflection of a certain time from when a comic has been released. Now only thing I would say is if they continue the contract idea they could implement a story based stuff with it when new items or hats come out. Each item connects to the comic in some way or back story etc. But for a complete story mode, I don't think it would ever fit since as I said before, its in the comic and in multiplayer game play. But that's my opinion lol

I think it could work but not with all classes being available at every stage in that kind of game mode. Each stage/level would probably have to be designed for a certain class or a few classes with it changing which ones each stage/level. If not then there would not be any incentive to use other classes because one or a few could blow right though a stage/level when another class actually has to work their way through it. If it's made harder for one class in this situation then it hinders another one even more. That said...

Would it be a little late in the game for Valve to add a single player mode? Then does Valve really have enough resources in the TF2 department for this?

It would have been nice to have a single player mode at or near the beginning, but it is too late now for that. Even with a Quake 3 or Unreal Tournament style practice mode, players would have had no excuse not to be already familiar with how the game works in their first multiplayer TF2 game.

I always thought it would have been a singleplayer like quake 1: go through an array of large and confusing levels and find keys and open doors.

This would work pretty well with bots too.

This would be awesome to show that people still care about Singleplayer games to prove the creator of COD that you should provide a Singleplayer campaign.

Someone should make a Mega Man-style game where each class is a boss character with their own level

And instead of Dr Wily as a final boss, you have Saxton Hale