After being helpfully chastised/reminded not to use outside art, I cobbled together a quick and dirty set of cards in Photoshop and then texture-packed them:

On the design side, I embarrassingly couldn’t find any poker cards in the house… after a quick trip to the drug store, I returned with caffeine and cards. Physical testing (me against myself):

It’s kind of a loose interpretation of the theme…

You only get ONE card for offense.
You only get ONE card for defense.      (ok, that’s two cards)

After the initial cards, the rest are dealt one by one to each player. They must choose whether to put that card into their attack or their defense (which royally screws with regular poker odds). At this point your attack will go against their defense and their attack will go against your defense. Repeat until someone dies!

Also might go more Puzzle Questy with the mechanic–each time you cash in an attack/defense it charges your attack/defense skills (like XP into those stats). With that mechanic I could shim in a simple level progression for attack/defense and just make it an arena battle where you keep going against progressively stronger opponents.

Time to start building a simple card/deck model in C#.