Game ticks in increments of in-game time. Calculate energy usage, distance traveled, passenger status, etc. each tick.
Base class for vehicle. Instance gets modified when modules, passengers, inventory, etc. get added. Contains properties for energy, cabin temperature, damage, etc.
Base class for things that go into vehicle that has weight and volume properties, image(s), sound made when added or removed from vehicle. Inherited by items, modules, people.
Base class for people with name, dialog tree, skills, fatigue, hunger, thirst, status effects/health
Base class for modules that calls its update routine every tick