Please choose Terran, Zerg, Protoss.
You are all (Starting base, workers) small squadrons sent by your leaders to harvest a large mineral node on the center of the planet. You are all in your own little base, surrounded by a high rock wall except for a chokepoint near the front. In these bases are a few scarce minerals and a small Vespene Geyser. (Numbercraft!)
Our Hatchery has completed. We begin mining, with no scouts. Our lone Overlord keeps watch at the chokepoint, wary for any threats to the Hatchery.
(50+50=100, 100 minerals, 0+0=0, 0 vespene)