Tried the last level again and again! Felt like I was -so close- but never managed to do it. I'd prefered a WASD movement instead, since it was really awkward to switch hand positions when you needed to make a quick mine and jump. I was very intrigued by this game, I'd probably play it for a long time if there were more levels and an easier curve. :)
However, I do feel the minute limitation here was more or less pointless, during the first two levels you'd actually had to struggle a lot to get a time-out and when the second miner arriver in #3 and #4, he would be so fast that the game would never go on anywhere near a minute.
Other than that, solid concept, presentation and enjoyment! I wish there were more levels, and that the AI for the miners were somewhat more random. :D