Uh... if you play the safe levels where you start off with 3 keys, you can always just instantly open the gold ones for a huge profit... unlimited money anyone? (Maybe the dev should fix it?)
This game becomes really easy when you find out that you can run the ball in... and all you need are 3 stats then (hint: they rhyme with spleed, stackle, and stoughness!)
for the wizard, shoot his fireballs and they'll go back towards him, destroying his shield so you can kill him. for the tank, just grenade once and he'll pop out so you can kill him, rinse and repeat. getting the minigun early makes this game a piece of cake
18110 first try on impossible... once the "robots" start to mob you it becomes literally impossible unless you can type over 150 wpm or something (I hit 110 on a good day)
Only thing I didn't like about the game was the lack of a quest log or whatever, somewhere to track what quests you have done/are doing... Hands of War had it :\