It sounds like the infestation landmark is being removed later on. I think it could be replaced with a similar feature that is designed differently, which spawns based on the enemy types allowed or its own advanced options.
Landmark:
Creature Pack:
Landmark:
- Spawns a "mature" creature with a pack of "young" creatures (Rove/DCT beetles with many of respective larvae; L wolf spiders with many T wolf spiders).
- Food yields of corpses are not affected by difficulty.
- Cannot roam or invade nests.
- All member creatures spawn at once, and don't respawn.
Creature Pack:
- Spawns independent of landmarks.
- A unique enemy spawn, similar to uber creatures.
- Includes varying sizes and types of the same creature that spawn at once and move as a group (and presumably don't respawn).
- Could include groups of ants of the same colony, potentially with upgrades.
- Roams and invades nests with the same rules as uber creatures (probably shouldn't invade nests if ubers don't).
- Pack types that can spawn could be customized by an advanced option (or tied to the creature spawns like uber creatures are).