You can unlock addition characters by playing Adventure Mode. Each character is unlocked simply by passing a certain chapter. There are no star requirements.
Schezo and Feli: Complete Chapter 4.
Draco and Witch: Complete Chapter 5.
Lemres and Dark Prince: Complete Chapter 6.
Ecolo and Ex: Complete Chapter 7.
Tactical, beautiful, and wholly unique, the GOTY-winning sci-fi RTS returns with Homeworld 3. Assume control and battle through fleet combat in dazzling, fully 3D space while the award-winning story unfolds on a galactic scale.