I was also wondering the same about the troops. I was sometimes using loads of money on them when I didn't want to use them. But still a pretty nice game.
Love this game. I felt I was pretty good at geo, but I see I have some way to go before I can call myself an expert. I got to level 7 in 4 tries and think that's ok.
Amazing game, one of the best. Now we just need even harder levels. (Only 15 was hard enough to make me a little annoyed... and I love solving puzzles that make me annoyed.)
This game is sweet. Really nice, smooth, controls and fun with all the different enemies. But I was kind of disapointed how easy it was. Finished the game in first try.