Zomb... Traitor Mechanic

Hey,

I've been designing some games back 'n forth for about a half year right now, and I tend to start on new games way to often. Most of the time its because I tend to make the game too complex and lose interest in it. This time I've tried to keep it simple, but thought about a interesting mechanic and need some input on it.

At the moment, I'm working on a co-op zombie game, where the players are locked in a house and need to survive against waves of non-player zombies that attack the house.

Basically, each player receives a hand of 5 blood cards at the start of the game, these cards represent a portion of the blood in their veins. There's two types of blood cards, 'Pure' and 'Infected'.
At the start of the game, their hand only consists of 'Pure' cards. The players hands of blood cards are kept secret from the other players.
The remaining blood cards form a blood deck.

So lets follow Player A from the start of the game, which means Player A has 5 'Pure' blood cards.

Player A then needs to smash some zombies in close combat to save ammo, but fails to kill everything and gets wounded by the zombie.
At this point, since he gets wounded by a Zombie, he needs to draw 1 blood card from the blood deck.
He draws a card and notice its infected.
This means that player has to discard one 'Pure' blood card. (When wounded, draw 1 blood card and discard down to as MANY infected cards as possible). When discarding blood cards, discard them face down.
So Player A now has 1 Infected card and 4 'Pure' cards.

After each game round, the players enter a "infection spreads" stage, and their infection (if they have one) might spread.
This means each player draws 1 blood card from the blood deck, and then:
- If they had one infected card previously, they discard down to as many infection cards possible
- If they didn't have an infected card previously, they discard down to 0 infection cards

So lets say Player A drew an Infected card, this means he now has 2 Infected cards and 3 'Pure' cards. (But if he would have drawn a 'Pure' card, his hand would have stayed as it was)

Okay, but whats the point of all these cards?

Basically, if the character ONLY have infected cards, he becomes a traitor and gets his win conditions reversed.
Additionally, if the character only have infected cards and gets killed, he doesn't die but instead becomes a Player controlled Zombie.
If a Human player (a player with 1 or more 'Pure' blood cards) gets killed, their character dies and they get a new one, unless the reserve characters are depleted, in which case the Zombies win.

The main problem I see with this mechanic is the following.

Theres 3 different ways of discarding blood cards after you've received them;
A - If wounded (or some other cases) discard down to as MANY infected cards as possible
B - In the "infection spreads" phase, discard down to as MANY infected cards as possible if you already had one, else discard so that you have 0 infected cards.
C - If healed (or something positive like that) discard down to as FEW infected cards as possible

The main point to remember is that you always have the same number (5) blood cards on your hand at all times. But it could get tricky to remember what to discard when.

The next problem is, you'll have to trust the players not to discard the wrong cards. This isn't a problem around here, as we really don't cheat, but what do you guys think about that?

Do you, more experienced designers, find more problems with this mechanic? Do you think its overly complicated?

Theres quite a lot of other interaction going on with these cards, like having players beeing able to show one of their cards to the other players to prove his loyality, or getting to look at 1 random blood card belonging to a player.
Players also have to face the dilemma of shooting other players before they turn Zombie to make it easier in the long run, even if it depletes the reserve characters. Or maybe as a 'Traitor' claim thats what you tried to do, but instead just have fun killing them.

Thanks for taking the time to read my wall of text,
SuperioR