Units
All units fight from distance and hovering over a human will display its range. Each unit has its own preferred height compared to the enemy and will receive increased bonuses when attacking from their preferred height. The amount of health units have depends on game difficulty.
The number of units that can be trained is limited by the Military Capacity, which starts at 10 and is increased at the Citadel. A rally point can be set by selected by selecting a building that produces units and right-clicking where newly recruited units should move.
All units have an Oxygen maintenance cost that scales with the game difficulty. Units received as reinforcements during a mission do not have maintenance. The time it takes to train a unit also scales with game difficulty.
Each unit has one upgrade in the building they're recruited from and one skill in the Book of Insight.
During all missions except tower defense Iris will be playable as a special unit. Iris can gain various passive and active skills via the Book of Insight. If she is killed on City Building missions she resurrects at the Citadel after a short time. If she is killed on Expedition mission the mission fails.