Now this was really good, I don't know what spacehulk is, but if that's inspiration for this, then I'd say you did a good job on it.
The strategy needed to win is what won me over, there isn't any other way to play, you need to think it out, before the timer runs out. And although difficult, that doesn't mean it's not fun. Some things are left up to chance, but that's in every game.
Overall the movement being slow adds to the planning of the game, and the levels of the demons are what make you have to account for everything. I wish there were a few more ways to do things, like different enemies, and different units for yourself, though I think it was just solid all together.