Gameplay mechanics

Money

Money is gained primarily by performing missions. It can also be gained by more overtly criminal means, such as killing people?, stealing cars? and selling cars. If money isn't gained by killing ordinary people, do you get any for killing zombies/terminators? It would be an incentive to do so, considering how tricky they are likely to be to kill. Or perhaps you only get money for neutralising a significant number of them, or helping a human faction retake some of a city, etc.

Money can be spent on goods and services such as weapons, car repairs/resprays, armour, passports/train tickets, etc.

The player also has a score mutltiplier, which affects how much money he gets for performing activities.

Lives

Reasons for having lives:

Reasons against having lives:

Conclusion

"What happens if you die in the middle of the desert?" is perhaps the most important point above - and thus, the following plan is made: You can only be resurrected if you are in a city/map with a friendly/neutral hospital. This means that the player is free to fool around inside cities, but if he wants to go out into the desert, or into an abandoned (i.e. zombie/terminator) city he'll have to behave much more seriously and be more careful if he wants to survive. This should allow the game to be fun if you just want to cause carnage, yet still retain a serious tactical side for some of the gameplay.

Alternative take

Still use the "no hospitals in the desert" rule above, but make the game use money to pay for healthcare instead of lives. This makes a certain degree more sense than removing the player's lives when he goes outside a city, and the healthcare cost could even be scaled by how much the faction hates you, etc. And if you run out of money, you're dead.

Zombies/terminators

Zombies and terminators will work using a dynamic population model, to give the game a more open-ended, unpredictable flow. Each map/city/zone will have population counters (contained in the mission script?) indicating how many of each faction there are in that area. These numbers will change over time, and depending on that areas relations with the neighbours, there is a chance a zombie infection could spread, or if the terminators wipe out all the humans there's a chance they will move on to another area, etc. The player's actions will also affect the flow of zombies and terminators, as if he disables a city's defence systems there is an increased chance of a zombie infection or terminator invasion.

Some cities will have been overrun by zombies and terminators completely, and will form the basis for some of the tougher missions, as the player will need to make an extended "road trip" to the cities to carry out some tasks - he will have to fight his way in, perform the task, then fight his way back out again.

Unfortunately the dynamic aspect of the zombie/terminator system will mean that if a city falls to them, missions revolving around that city or factions within will no longer be available. If the aim of the game is to unlock the cities, it's important for the player to still have a way into a city if it's been zombiefied/terminated, otherwise he will be unable to complete the game. Also it may be worth placing a max zombie/terminator population count in the game, so that they can't take over the whole map without the player being able to explore it a bit first.

Other possibilities are available when working with the population model system. Inter-faction wars, or genocide on behalf of the player, are possible occurences if the system is designed right - but will place a greater emphasis on dynamic missions as opposed to static ones, and will require more careful design to ensure the player has a chance to see a good number of the missions if he at least attempts to complete the game by performing missions.

The population counts contained in the mission script will obviously also affect the populations and faction makeup of zones as seen in-game.

Resurrection

Some zombies have a chance of resurrection. Burning them, exploding them, or smashing into them at high speed are all effective methods of preventing this.

Radiation

There's been a nuclear war, so it's natural that there are some irradiated areas. To keep things simple, it'll probably be a case that there are two levels of radiation for a map block - on and off. However in order to make it a bit more complex than getting your hands on a radiation suit, radiation timers will be used - certain vehicles, clothing, etc. will have a certain timer value. If you stay inside an irradiated area for too long, the timer will elapse, and you'll start getting radiation sickness. This sickness will result in loss of health (and eventual death), unless you get back out of the irradiated area (or find medkits, etc.). Once you're out of the area, your radiation sickness will slowly dissipate; essentially the radiation sickness has its own timer (or corresponds to a negative timer, etc.).

Cars will also be subject to a radiation timer - if a car stays in an irradiated area for too long, then the car will become irradiated itself, and will irradiate the player if he enters it.

How to kill a car

As TIB doc

Auto-adapting difficulty level

Desert

TODO:
MUST-DOCS: UNKNOWN: Complete money design
MUST-CODE: UNKNOWN: (Design in more detail/)Implement radiation system
???
Profit!