Awesome game, no doubt about that.
There is quite a few suggestions that I believe would be mega awesome though =D
Suggestions
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1) Campaign mode! It would be very interesting to have different levels to play, with increasing difficulty and unlock ables. Maybe even a storyline if you can throw that in!
The game is quite stiff. Its not so fun to play the game with just one objective. A campaign will definitely bring in more.
2) Stat system - In addition to a campaign mode, implementing stats would give whole new options! Attributes of strength, speed, agility, and such.
3) More Strategic Gameplay -A follow up to a stat system, the game should be more strategic. It should be more then simply sending your men to hunt each other. Modify the battle system so its more interesting and less predictable. Also, maybe be able to hire an engineer to fix the buildings?
4) Player vs Player - Now this would be quite hard since you cant have two mouses, but if you are able to code it so it is playable with the keyboard, or a turn based system, it would be nice.
5) Multiple paths - Just to add on the intensity! We need more to do then just click. Multiple paths would make it hard =D
6) City vs city - Why make it just a building vs building? Why not an overview play of the game! A whole city!!! Attack one another, build castles, towers, harden your walls!