If there is an update. Letting people already playing know with an in game notification would be a good idea, e.g. a 'gift' popping up to say there is new content available in the new patch or something like that.
These headphones should be a thing to wear in the game :3 (it can also be a thing in real life: https://www.indiegogo.com/projects/axent-wear-cat-ear-headphones )