- Spawning pool
- Evolution chamber
-Creep (purple snow with added properties)
Like the zerg, it all starts from one drone that spawns randomly at a low chance both night and day. The drone can attack other mobs after it makes its first kill it will move around to find a place to morph into a hatchery.
The hatchery produces a few more drones at a continuous slow rate to a maximum number (maybe 3-10) which will look for mob victims to consume and after they do so, they will all look for a place to morph into a spawning pool.
When the spawning pool is created the hatchery will start to produce zerglings aswell as drones with a larger capacity. (Overlords could be optionally added which increase the hatchery max mob.) After the zerglings make a few kills collectively the drones will attempt to morph into an evolution chamber which enables a queen to spawn.
Once the queen is spawned, the hatchery can produce faster and the queen itself is a large threat.
tl:dr? Zerg grow by killing monsters and the swarm develops in tiers of accomplishments.