I believe this may be a glitch, but when you go to build, select a square and then wait until an enemy unit is standing on the square once the unit is at least 1/2 way on the square make(drop) the tower, it will insta-kill that unit. This is a very easy way to beat the game without many upgrades... if any.
Overall the game was ok. Its a fun idea but needs major rebalancing. The first thing i would change would be to add an accuracy upgrade, and eliminate the potion upgrade.
Place towers starting at the left side and stretch to the right. Only use damage towers, not slow towers. Pattern from top to bottom is space-tower-space-space-tower-space-space-tower-space, so you have 3 towers in each column. The first few waves you'll lose, but you can beef up your crap and try again.
If you get to about 1000 gold with nothing to build, add an extra line of towers.
When the knights are almost getting all the way through, switch to a maze strategy to make the go back and forth through your columns of towers.
The trick is to place the towers after the wave starts, try to block the path that the knights take.
I recommend!
Not bad, but the fact your towers dissapear after 4-5 shots where annoying. Oh, and don't forget about the horrible accuracy.
boring