I beat my first sector today, somewhat of an overkill because I'd been building lots of fliers and units. I still don't know what most of the color's properties are, but I've gotten much better at surviving.
This game could REALLY use a save feature. Just something to freeze the game for when you come back. As it is, if you're going strong and suddenly have to quit, exiting the game means you don't make it on the high score table (which isn't really a big deal to me, but it's sort of fun to read the stats on my current run).
I'm not sure placing walls is worth the time. In all the games I tried that, I got overwhelmed, but in my recent game I didn't bother and was able to clear a sector.
Anyway, props to Toady. I started off completely confused by this game, but after figuring out enough to play decently, it's pretty fun.