LessaWorld Company is currently running a Kickstarter campaign for Endurance, their new battle card game. They've also set up an electronic version that you can try out in order to get a feel for how it works before you pledge, and also get involved in playtesting, since if you find anything that appears to be broken, they'll fix it before the game gets to your doorstep.
The game's rules are rather straightforward. You play a Damage card that has one of 6 different colors on it, and can add in a Power Card to boost it (but only if it shares a color with the Damage card). Your opponent must then try and defend with a Savior card (again, that must match colors) or a Power Card of their own (some of them are negative amounts. And again, you have to match colors) to try and not take damage. Play goes back and forth like that until one player is out of health.
Now that I think about it, it's almost like "Battle UNO" of sorts...
Anyway, the campaign is up and running now, with 25 days left on the clock to make it to their goal.