Etherlords is a combination of turn-based strategic war game and card based battle game (a la Magic the Gathering or Pokemon the Card Game). You can hold duels, but the main feature of the game is that of the campaign, a story played out either through the side of the peaceful Kinets and Vitals (the Kinets being very air-focused and Vitals being very earth-focused), or the war-like Chaots and Synthets (The Chaots focusing more on fiery themed attacks, and the Synthets being a death and sacrifice themed race).
In each campaign map, you control a set of heroes summoned from a castle to complete an objective, usually to move about the map making the heroes stronger with the main goal of destroying the enemy castle or castles.
The campaign for either side gets very hard very fast, even on easy, where the enemy heroes are more obviously "cheating" (i.e. they lose less of the battles than a human player). This seems to happen regardless of if you allow the computer to fight for you (a valid option in some cases) or if you tactically fight the battles out yourself. The enemy also seems uniquely equipped to contrast your attacks. If you have played the original Pokemon games, a good 80% of the battles with enemy heroes feel like the first battle with Professor Oak's grandkid, Gary.
This would be fine if the battles were active and interesting, but this is more of a slow, steady, slow burn game. So a battle, even a simple, normal one could take 20-40 minutes only to lose and have to reload from wherever you last saved. Also, because this is an older game, you must purposely save, or that 20 minute battle against a rat that went sour for your neophyte warriors will need to be fought again. And then you do it again on the next map with different heroes.
The strangest thing is the final battle, fought with a max level hero and any spells you want against a single foe, is meant to cap the story, but feels more like it was the intention behind the game all along; to have a single hero leveling up, gaining spells/cards and finally fighting a foe. As if the original plan for the game was more of an RPG card game hybrid.
All of the patience for a turn-based strategy and a turn-based card game without any real payoff in terms of story or continuing gains makes this a game I cannot recommend.