Okay...I failed underground the first time, the second time i try it, I'm immediatley surrounded by about 10 tanks and subsequently demolished...Fair much? 3/5.
Pretty cool, 4/5, But im pretty sure its impossible to kill a elite skeleton...I've only killed one so far...the rest of the time i die when the skeleton has about 214 health left or so...
Once you get to higher levels, the game becomes hard enough on its own without the time limit...Mabye make an easy mode with no time limit? Other than that pretty cool, 4/5.