The game was fun, and I slaughtered it, but it has loads of issues. It lags like mad when you spam your soldiers, which is the only way to win. If you get 10 or more archers they all get surrounded in a black box and there are black lines all over the screen when your army marches forward.
There's basically no difference between easy mode and extreme mode, so I found out quickly that playing through on extreme mode would save me hours of time. The game only took about an hour to beat because an army of archers and legionnaires is highly unfair to the enemy; and having your miners on cocaine speed makes collecting money far too easy. There is one level that gives up way too much gold, so that you can just buy your way through the later levels.
There aren't enough stars in the game too, because I was only able to fully upgrade 3 units (miners, legionnaires and archers) so every other unit was a waste of time. The art style is nice but the English translation is pretty terrible, plus your legionnaire and your general have the exact same face, so I never really knew who was talking. Each and every level consisted of basically the exact same dialogue: "Can we do it?" "Yes we can" "Yes sir!" basically sums up the dialogue.
Each time a unit is hired they make an awful sound or expression or whatever you want to call it (the archer and miner both sound down syndrome-ish). Still I did have fun murdering the game. However some of your achievements are broken (for example you can't get the achievement for upgrading your tower unless you purchase the low upgrade before buying the actual good upgrade). Also if you play through on extreme you can't unlock the *complete the campaign on hard, medium, or easy* achievements. Also, why make achievements but not Newgrounds medals?
The last gripe is that at the end you show a massive Viking behind the wall that you should have used as a final boss or something. He's just there for decoration though, which was a huge letdown.
I'm sure you put a lot of effort into making this, and I'm sure you'll do even better next time. Keep up the good effort.