Refreshing twist
This an interesting reversal of the tired old "defend your castle" geanre. You managed to make a RTS, and that alone deserves kudos.
however, that said, there is room for improvement here. Like many have said, your choice for hot keys was...well to be blunt, stupid. Fortunatly that was the only "dumb" thing you did here. I would have liked to have seen my troops carry over from one mission to the next, thus giving me a varitable LEAGION OF CASTLE CRUSHING DOOOOOM-oom-oom!!!!!...after a while. Another thing you could have done here, is set up a castle of your own where you can see all your little bees (troops) going about their happy little business, training, reserching, and whatnot, in between missions. Better yet, you could have the ability to take over a castle, this could add more depth an meaning to the game as then you could have a crude map, where you could chose the castles you want to take over.
I keep refraining from saying the obvios next step here, and that would be having missions where you blend this new take with the old, and then produce a very simple (but infinetly mor fun) true RTS. Franted it wouldent have resource management, but then, I alwas foun that that takes avay from the point of those types of games and in the long run just ends up destracting you.
Sorry for rammbling :p