Sugg - Include the free dlcs as base game and add achievements

Im not sure why you chose to do this, but if the DLCs are free, they could be as well part of the base game. This way you could also add achievements for the new maps: completion, exploring, garage unlocking, and maybe some random achievement.

because this way it was possible to release the game and when other content was ready release that?
Just thinking...
And AW DLC was probably not planed at all when game was released. It is likely it was added after comminity wished such thing...

You can release new content as any normal update. They are just files.