Developer Red Fly has been hard at work tweaking Mushroom Men: Rise of the fungi, taking into account feedback it's been getting from focus groups. After IGN's last play test they reported that the different unit types were serving as the game's difficulty levels. Playing the game as the Heavy, Sage, or Scout would result in easy, medium, or hard settings, respectively.
But apparently, the consensus has been that people want to be able to choose a unit separate from the difficulty, and maybe play with the heavy on hard. Now IGN can, as Red Fly has unlocked the units from these settings.