Thanks to everybody who has tried the rough draft and told me what they think; I've learned a lot. The main things I've learned are:

-Breaking the game up into levels works.

-Mouse controls are unintuitive when a player needs to quickly react to an ogre attack.

-No one really knows about or tries country linking.

-It's fun, but not super fun.

Response has been favorable enough that I'm going to stick with this general structure (levels, ogres, et al), but it's clear that it needs a lot of work. People also had several good ideas, and I have some of my own I'm going to try. I'm going to add some of the easier stuff and shoot for posting an update next weekend.