You pick a spawning unit from 7 factions made up of 4 races (Borg is the 4th). You can switch your spawns at any time. Each faction has strengths and weaknesses to other factions. Each faction also has 3 tiers, so that is 21 ships total to use as your minions.
There are as of now 18 heroes with distinct purposes/abilties to recruit. Thats another 18 ships!
You must protect your planetary fortress while trying to kill the others.
Custom unit attributes are in play. This means instead of vs armored, mechanical, etc, it will be vs Borg, Zerg, Protoss, Dominion, etc. This allows for easy balancing of the 7 factions by giving a faction a bonus vs another faction if it is too weak against that faction for example.
-Upgrades and abilities:-
You can upgrade your spawning units, your heroes, your planetary fortress.
You can also research abilities for your planetary fortress to ward off enemies such as missile pods, a seeker missile, guardian shield, cloak, build turrets around, and more. [remininscent of Ultimate Tank Defense =) ]