Save states and the Evercade

How do the save states work on the Evercade?  Are they based on a game by game basis?  I started using them on a couple of games and I thought I might lose progress in a previous game... so I didn't use it on the new game.  Has anyone experimented with this?

I figure this thread would be best used in the Game Tips section as most people will want to use the Save States on their Evercade.