There needs to be diminishing returns on money or something. All you have to do to win is surround your castle with a wall 2 layers deep and put level 3 infantry on them. Cannons and such are just a waste.
This game's economy really needs to be retooled such that there is a point to upgrading the units. As it stands it is mathematically advantageous never to use special units or upgrade units... or use dexers (except on Rat Trap)
This is a pretty lame game, but I played it through because my dog is a greyhound. I can only think of two games where I got to name my dog... this one and Earthbound I think it was.