This was a decent play. The game wasn't terribly amazing, but it wasn't boring either. The units that the heroes brought with them were nice, and helped with the enjoyment, but you should try to find a way to keep them all from stacking up like that. It's not particularly elegant, even if it looks neat in some ways.
This game I lost to on moderate. I don't know if you had the difficulty triggers set, but the medusae killed my centaur and the shot Arkantos to death before I ever made my first turn, but right at the end of that length.
Overall difficulty wasn't too bad. It wasn't too easy either.
The map, as said below was good to great. The story was... there. But not explained. So I can't really give you anything for it. But the idea of the under world was a novel one to me. However, if I was you, I'd have used the cave wall on the sides of the map to hide the blackness a bit. Keep the cliff edges, but hide the edge of the map with the cave. It'll add to the effect of the 'Underworld'.
Map Design: 4
This is the whole reason I'm giving you this review. Those cliffs, while annoying as all get out, were awesome to look at. I liked the way the colors stood together and the black rock in the bottom did a good job of making it look like a long ways down. The city itself could have used some work, but the lack there paled next to the success of the cliffs. Good job.
Add more story, add more instructions, and then I might have something to write here. The story that was there was nice enough. But wasn't well enough told.
You also might want to consider changing the time to complete thing. The notification that I had a given amount of time, and the time I had were different. One hour is sixty minutes, two hours is one hundred twenty. I can't remember how long I was supposed to have....