Can't play multiplayer for god knows what reason and I'm getting bored in single player. Can anyone recommend me a really good mod for SP that will add alot, change up alot, and just in general make it more fun?

If this should be in the editing board, feel free to move/lock it and I'll repost there if needed. Just thought to ask here instead.

And would my current savegames work with it? I don't feel like doing the SP campaign again.