Way too easy
This game was just way to easy. You could either spam the enemy with a mix of infantry and archers, or even only one of the two, and once you had enough money you could upgrade them to a degree where one archer can take out the castle if missed often enough. Towards the end I won regularly with only five archers. I gave up on upgrading them because I had too much money and the enemy didn't stand a chance this way or that.
And how on earth do you get the other five units?
With a bit of work though it could turn into a decent game, so I give you 5 stars.