--Resources and Base Management.--
It is possible for the players to establish a safehouse. And if they so wish, grow it into a proper base which can be the safe haven of the city's survivors. The base can then be upgraded and exapanded upon to provide passive income on resources, speed up healing, give bonus to some rolls or even provide NPC support depending on what the players invested in. Note that some upgrades require electricity to run. This can be obtained from solar panels or generators that run on units of fuel.
Resources are generalized. And while the supplies you get from going out scavenging will be detailed out, it will be converted to a general unit once it's been safely tucked away somewhere.
Several planks of wood could be 10 units of wood, for example.
Ammunition works similarly. You may get a detailed overview on what you've looted, but when it gets stored away, it gets converted into units of 'Munitions'.
Every player can carry a certain amount of ammunition with them wherever they go. This can be refilled at safe-houses and bases by taking some out of the storage, or scavenge around if you're lucky. You don't track individual bullets or magazines, but in 'Munition' units.
You spend Munition units every time you use your weapons in an encounter, the GM will decide how much Munitions you've spent depending on how long the fight was, how many attacks you've made and with what weapon.
Obviously, a .45 pistol will eat up much less Munitions than an assault rifle or a rocket launcher would per attack.
If you run out of Munitions, it means that the next encounter you run into, you'll be going in without bullets to shoot. So be careful! stay stocked, or try not to shoot everything that moves, eh?
--Animals and you.--
Eventually you may end up taking in other animals to help run your base. These animals will need food and water or else they will become sick and die. Sick and wounded animals will require units of medicine to heal up, having others who have skills in medicine will help speed up recovery drastically, thus saving you precious medical supplies.
The players yourself also need food and water to survive. Even without a safe-house yet, each player will be able to carry with them units of food and water that will allow them to go on for several days at full ration capacity.
Watch out for the cold too! if you or the NPC animals is exposed to extreme heat or cold that their bodies can't handle for too long, they can die!
--Turns and Choices.--
There's only so much you can do in a day. And in order to keep things moving, the day are seperated into 4 parts.
2 parts day, 2 parts night. 1 of those is when you'll have to sleep. It is possible to force yourself awake, but that's not healthy and you will suffer penalties for not resting. But sometimes, you just can't afford to sleep.
Now, a single part per day is assumed to be 6 hours. Minor choices such as visiting people and talking to them are free. These 'parts' are only counted for when the players decided to explore a major location, like an entire block or streets to scavenge and such. During this time, they can encounter survivors, infected, looters and of course, loots.
After all 4 parts are spent, the day is over and units of food and water are ticked off. Don't worry if you run out of food and water, you won't die immediately. But you should probably try not to run out of the essentials.
And that's all for now, feel free to ask if you have any questions!