The main design element of the game is the health vs food vs strength tradeoff. Let us first consider food and health.
Every player starts with 5 or 6 health points, 2 or 3 pieces of food.
Health and food are closely related. Each day a player must consume a piece of food or starve and lose a health point. More food is gained by scavenging which usually means fighting zombies. Getting in a fight means running the risk of lose health, so there is a risk-reward tradeoff. Fight and there is a chance you will lose health, perhaps a large amount if things go unexpectedly badly. Or else run away and face the certainty of eventual starvation.
There is also an interesting tension between health and food. The starvation mechanic seems to set a 1:1 equivalence between the two, but food and health are not equal. Food is transferrable, health is not. A player with 2 health and 3 food has more power than a player with 5 health. They have more options for trade and negotiation in the party. However they are also in more danger. Low health is risky and invites attacks.
Health and food are both tuned to be on a steady decline. There are only two opportunities in the game to regain lost health (the Hospital and the First Aid Kit). The are rare and often do not appear at all. If they do appear the players have to decide when to use them. Too early and they may be used on a player who does not need them. Too late and players may die before they have the chance.
The rates of health and food loss are deliberated tuned so that four players are likely to hit zero after about 9 days, depending on the distribution of cards. The road deck is tuned to take somewhere between 8 and 12 days to reach the airfield. Three players can survive longer – they have less fighting power but they consume less food. The gain in food usually outweigh the loss in strength, assuming no-one is hurt in the process. Of course, most parties will not consider this option until the food supplies are already too low for it to matter.
Then there is the cannibalism option. The party can exchange total health (and strength) for temporary food by letting one of their number die in combat (or deliberately killing them). This is the only way that health can be transferred, and it is deliberately drastic. Players who starve to death cannot be eaten. While this may be unrealistic, it forces the party to make a deliberate decision to kill their teammate, rather than just letting them die by “natural forces”.