Just realized why I like this game so much -- it's the first defense game I've played that actually felt like there was an actual *point* to what was happening. Maybe it's the pseudo-historical aspect; maybe it's the part where you're building fortifications rather than simply 'towers', but it really feels interesting.
Not bad. Poor UI design - no obvious ways to quit, change music preferences, etc. once past the main menu. Good level design, though, especially the lasers - makes you think and work without being unfair. Bosses sort of meh, and the level 9 boss is a perfect rip-off of Tyrian 2000's first level boss. Eh... 4/5. I keep coming back to it.
Good effort but it REALLY needs the bugs worked out. I love trading/conquest games like this, and there's a certain level of humor in the game that speaks to me, but the extraordinary quantity of bugs makes this pretty much pointless to play.
Superb as it is, and it will quickly become a web classic if you follow KittenFlaps' and koaladood's suggestions. Remember, too, that when people actually bother to suggest specific bug fixes and changes, it's because they like it enough not to shrug and try something else...