It's nice
Pretty good so far, but the assassins are too good.. they shouldn't be able to dogde the fireballspell.
And there is a bug which i regonniced in lvl 14: even i have some gems left i lose the game, when an enenmy just get away with another one.
maybe its because the gems returning skill i have...
Generally - Nice
Really good 'defense' type game. I liked rpg elements and talents tree like in wow,so you can customize your gameplay more and get different game experience than some one else :)
To Be Honest
I feel this is the best tower defense game I have ever played. The only thing I can point out is that each tree pretty much defines what "end game" tower you will use, i can get gold on everything going the route of orc den for green, fear tower for blue, and single target searing for red, I rarely found a moment where there was enough targets on the aoe for red to make it worth the slow attack speed. Other than that the game is awesome, keep it up. Hope to see more from you.
Left over SP?
Well like mentioned before, the skills are flawed. And the Ninjas are way too fast/strong.
Also, what do you do with the Skill Points when you have everything maxed out?
Weakness
The Bosses are too weak. Well, one of them is coming, taking one gem and leaving. if I just want to pass the level, does this really hurt me?