This game is, frankly, awesome. The shadow mechanic, while not quite original, was implemented uniquely. I especially liked the final level, where, with enough tries, you can just brute force your way through.
You know, the Gem Waster actually is worth it. Being able to turn 11 gems into a pick with almost double the ordinary base power of my blacksmith? Yes, please!
There really does need to be a way to convert other currencies into DP, even if it's as lopsided as 1 million Coins for 1 DP. Not everyone has the time to fight in the arena, and not everyone has the money to just buy DP.
You should make it so that Ambushes don't cost energy, or at least only cost somewhere between 1-9 energy. I went through 3 or 4 Ambushes in one area, and it nearly drained me so much that I couldn't fight the boss!
Heh heh heh...