Skirmish

Skirmish is a mode on Halo Wars which allows the player to battle against other opponents, either human or A.I., on various maps and under a variety of conditions. The player can select the number of opposing A.I teams, Leader types, modes, difficulty levels, and the map. Skirmish may be in Standard or Deathmatch mode.

Teams
There are three Leader types for the UNSC and the Covenant. They can be chosen from the Leader Selection Menu for yourself or for A.I. opponents by selecting a slot on the Alpha or Bravo Team. Also a random team Leader or both random can be selected.

The leaders you can pick from are Captain Cutter, Sergeant Forge, and Ellen Andersfor the UNSC). Also there is the Arbiter, Brute Chieftin, and The Prophet of Regretfor the Covenant.

Each character you pick has his/her own special abilities, upgrades and so on.