This whole franchise is amazing, and I know most fans of it will tout HOMM3 over 2, but for me, 2 is one of the greatest games ever. It's easily in my top 5 favorite games. It's the one that introduced me to the franchise, and it's the one I've spent the most time playing. It has more of a fantasy aesthetic as opposed to 3's more medieval aesthetic, and it isn't as balanced and strategic as 3, but it's that fantasy element and all the details in the differences among creatures and factions that makes the game endearing to me.
Turn-based strategy game where you build castles, develop armies, and use Heroes to battle the armies and conquer the castles of other Heroes. Fantastic soundtrack, memorable sound design, creative spellcasting, interesting artifacts, and (if you download fan-made maps from the internet) thousands of maps to explore and keep you challenged.