This is what paved the way for games like Fire Emblem to be successful.
Anyway, if you like Fire Emblem and think, "Wow, this is so revolutionary!" Well, you can think again. This is definitely one of the first few games of the whole turn-based, hexagon-movement variety. Playing it now feels like playing the same exact game as Fire Emblem, just with a larger variety of characters, spells and attacks and a less predictable gameplay and story.
The movement and attack scheme is pretty much identical to Fire Emblem. You start each battle on a large field with different obstacles and such, deploying your troops accordingly. (Hydras to the water! Dragons to the mountains! Everyone else, form up around me and charge the bridge! ...Epic!)
The main difference is in the overall gameplay. Instead of a linear RPG feel, this game has a more RISK feel to it. There are multiple castles around a map, ready to be conquered, each territory held by a different boss. Once you capture one, you have to leave troops behind to protect it, and so forth until you have defeated every castle.
The only downsides (and they're small) are the graphics and sound, but there's where you can fault the Sega CD.