To assist with mango's problem, you can just make it so you can destroy your own base at any time, thus making it impossible for the enemy to retake it, but also making you get less units...
Should be a create custom map after you win =D
Random events needed... bosses eventually missions would be good...
more to the buying of stuff.... but bonus's such as luck speed life and dif colors between your stuff and badies stuff on main screen... if this is ur first flash game nice work just keep it up :D