His Dark Majesty is a turn-based strategy game for 8-bit Atari computers, where players get to command troops in battle by issuing orders to units one at a time. The first few stages do an adequate job of teaching players about individual unit specialties and battle strategies, but to learn what each icon and status symbol stands for you will have to visit the FAQ section on the official site.
The one-button control works fairly well for issuing commands to your troops, and you can cancel orders by holding the assigned action key for a few seconds while the selection box is over a friendly unit. Carrying out the same action on an unoccupied tile ends your turn, and you can even examine an enemy unit's movement and attack range by selecting them.
Fans of strategy games who don't mind booting up the emulator will enjoy His Dark Majesty quite a bit, although large skirmishes and battles could take over an hour to play when both sides have plenty of units to order around.