Great game, but I have a few thoughts: It would have been nice to see what level my weapon and armor were at, like my jewelry showed, so I could have a rough estimate of where I was with them. Also, I would have liked to see the status screen show me a lot more-for example, the level of my various pieces of gear. It could help people get an idea of when to go back to town to upgrade their stuff ("I got 60 weapon stones? Sweet, time to upgrade me axe!")
I don't know if Mr. Undefined looks at these comments, but I think the line of code for Soul Drain is somewhat glitched. When it is used, the enemy takes the damage, and all my mana stays right where it is. Now I'm glad to have a reprieve from the late game assaults I take, but then again, my OCD forced me to try to make things work properly (which is why Bethesda games piss me right off)
I would say do a sequel, increase the number of demon types, and add a mode where you can freely spawn both towers and demons to test certain combos against certain critters. Other then that, it's a good game, but the difficulty does curve quite a bit (tis why I suggest the extra training mode). Other then that, perfect game.
Not bad, about the only change I'd make is to have prices fluctuate based on trades. For example, if a city has zero Spirits, they'd probably be willing to buy it at a higher price then a city swimming in booze.