I like the decision to save 2P separately from 1P.
Consider adding a save file version number now, rather than later. In case later you decide to maintain save files, with different game versions. This has saved us lots of headaches and made it easier, even though maybe a bit verbose, to maintain game updates for different versions.
Recently we also implemented achievements for the first time in a mobile game, and realised that it has so much value to us as developers if they are chosen with purpose. You can actually get more out of them if you use them also as a means to track player retention, etc. And this made it worth our effort more as a nice surprise, since it gave us valuable player behavior statistics.
Man I've been following this game, and I think it is time you share a vertical slice demo - please. I know you said "soon" well, it cannot be soon enough!
gamelancer
Morne joined
Crazy Indie Game developers for mobile platforms, focusing on HTML5 and Android using GameMakerStudio