Largely a remake of the much-loved Amiga game Defender of the Crown (later released for just about every platform available in the late 80s, including the NES), Heroes Live Forever updates the game with better graphics, fully digitized music, and a new gameplay element ("tactics" cards that give you special benefits during battles).
In Defender of the Crown, you play one of several great lords in England, attempting to unify the realm under your own rule. Conquering provinces produces tax revenues that you can use to increase the size of your army (but you have only one "army" which follows you, milord, about, and can purchase new units only at your castle, meaning you become vulnerable over time unless you return home frequently). Battles are fought out on screen; and joust and archery minigames can increase your "fame" (which allows you to earn more taxes and move farther distances). Conquering enemy castles requires (expensive) catapults.
When first published, Defender of the Crown's graphics were considered eye-openingly beautiful and a pointer to the potential of digital games; this version's graphics are attractive, but of course not at the level of big-budget mainstream games today. The gameplay remains what it always ways: accessible, and entertaining, turn-based strategy. It's well worth a look to experience a part of gaming's history, and learn, once again, that the dramatic technological improvements of the last decades have not, in themselves, done much to improve on actual gameplay.
N.B.: While the demo permits only 30 minutes of play, it can be played (for 30 minutes) repeatedly. So if, say, you want to read through the in-game instructions (which is a good idea), don't worry that doing so diminishes your time for the demo; once you're finished reading, simply quit and restart.