Warcraft: Orcs & Humans/Swamps of Sorrow

Building the five remaining Farms and a Barracks will cost 2000 Lumber and 3100 Gold in total. The nearest Gold Mine, due north of your Town Hall, has 3000 Gold left, so it's possible to achieve this without needing another Gold Mine if you only train two more Peons. None of the Humans attack unless approached, so only move your Peons to mine Gold to the north, and harvest Lumber to the south.

Select your Peon to build a second Farm, and select your Town Hall to train a second Peon. Once completed, select both to mine Gold until you can train a third Peon, then select two to harvest Lumber: the north Gold Mine is so close that a single Peon should be able to mine all but 100 Gold before the other two harvest 1700 Lumber to build the remaining Farms and a Barracks. Once all necessary Gold has been mined, select that Peon to build.

While you wait for your Peons to supply sufficient Lumber and Gold, you could do nothing (except perhaps open the Main Menu, select Options and increase Game Speed to Fastest) or you can select your three Grunts and send them on a search and destroy mission. All three will almost certainly be destroyed before they destroy every Human, but they should be able to find and secure Gold Mines further to the north and south of your Town Hall without loss.

Arrange the three Grunts in a line perpendicular to the direction in which they move and attack. The Gold Mine to the south is only guarded by an Archer, so move down the road to the south and attack and destroy him when attacked. The Gold Mine at the north end of the road is more heavily guarded, by a Footman on the left and an Archer on the right: destroy the Footman first to improve the chances of none of your Grunts being destroyed.

The last remaining Archer in the Swamps is through the trees to the southwest of this Gold Mine, by the eastern shore of the pool in the northwest quarter; all remaining Humans are Footmen. If you want to destroy them all, make sure a Barracks has been built first so that more Grunts can be trained to replace any destroyed, and that you have secured another Gold Mine to pay for them.