I've been tossing around a few ideas for games, I thought of one I think I'd like. It's a mix of Hearthstone and Pokemon.
You'd catch a Pokemon (I'm calling them that cause I haven't come up with a name yet) in an amulet...
In battle though, you'd be able to have only three Pokemon and they are all on the field at once.
You'd then draw five cards which all have Pokemon moves on them. To do a move you have to use a card that would have the Pokemon move on it. You'd pick the card and Pokemon to use the move. Then you'd pick the target. To draw anymore cards you have to use a move or discard a move card.
You would also have an item slot that you could use during the round. Once you use an item though it would have a price that locks out the use of items for X amount of turns. So low potions you could use every other turn but a Super Potion would lock the item use for three or four turns.
I was also thinking of having it be perma-death so if you lost a Pokemon you'd have to go re-catch one.