Alright, now it worked just fine. This is brilliant entry! Very, very intense experience.
I somehow felt some of the nasty cards were too nasty. It was difficult enough to get ammo. Would be nice maybe instead of buying, you could see icons of "ammo" or "health". And you'd need to combine those together. "Find 2 ammo cards". Or maybe there could be so that if you pick wrong card, one of the card vanishes (just an idea).
I think stealing my credits was something I have no control over, making this just chaotic - I lose all my progress, and all my strategy (memorized position of cards). Of course zombies could have more hitpoints, there could be different ammo types, different weapons, and boosts...
I would not allow infinite jumping,. or maybe so that "jumping" would require finding "jumping cards" and thus you would have "1 jump" that you can take. And in that case jumping should be "easy" and it should jump so high that you can easily go there.
I feel this might be great in "ipad" where you can tap on screen. Now I had to try memorize arrow keys and use mouse to flip cards.
Oh and one more thing: Instead of stealing credit/randomizing cards, I would maybe add cards like "zombie recovers" or "more zombies appear" when drawing certain card.
Overall: The concept is very clever. I think the design is solid. Very good entry. From gameplay perspective this is so far maybe the tighest/most tactical I've seen in ldjam41 (that boxing game where you glue dude's eyes is really solid entry as well :D)