Very basic, and entirely too easy. At no point were the enemy's units as strong as the players, and the maps were biased in the players favor throughout the game except for 2 in the middle with no guard towers. Just maxing guard towers and horses you can beat every level.
Add on 5-10 more levels(maps) where the enemy uses same level units as you and less guard towers eventually having none, or maybe even give the AI some to even it up.
I must say, I had fun on this for most of the day. Acquiring the physics lab really trivialized the 80+ missions. Deploying 2-4 of those with miners and interceptors would clear the missions/defend the base on their own, had to play really defensively to even see some of the spaceport ships.
Castle Guard
Obliterate Everything 2