With the change in numbers required for unlocks, it might be fun, albeit massively frustrating for some, to change the buy 1, 10, 100, max, to something like buy 1, 7, 65, max.
Good launch game. I would like to see a goal related to the theme, something like an enemy king at 50'000 distance or something. After killing the enemy king you open the unlimited, high score, mode. I feel that this would add some more interest for the game itself.
I did not have any issues with the cannon working. In fact I did not bother building any of the units, since the fully upgraded cannon one shots all but the spear men. Perhaps some tweaking is in order there.
 "(BETA) AdVenture Capitalist"){kind=icon}
 "Crush Thine Enemies"){kind=icon}
 "Fortress Barricade"){kind=icon}
 "Captain Cannonball"){kind=icon}