Do Steam WorkShop integration for better mods content. Do achievements, medals and trading cards in Steam cause it's fun. Do some easter eggs in your maps, for even more fun.
Tdev once said that they will implement their own mod browser and installer that will be even better than Workshop
I bet ya once career mode is in there will be achievements. Don't know about trading cards and medals, not very many people seem to want those.
Workshop support is a no, as was already stated, but also for quality control. Otherwise the workshop would be full of russian quality mods which would lower the overall value of the game. Achievements and all other sorts of steam flair will probably come eventually. The game is still in Alpha, and as of now there really isn't much of a game so much as a crash simulator. I'd like to see profile backgrounds for the game though.
