Fun idea!
You asked for some feedback so I can give some, I would say the combat part of the game is pretty fun, but there is too much narration before you get there, I would try weaving in the narration between each part getting discovered that would get people to start playing faster and still get to see the fun story. Also one cool thing you can do to help people's experience is add a "mercy timer" in your case I would let the countdown get to 0 and then wait a second and then blow up the world. That will create epic moments where people feel like they just barely got there in time, when in reality you gave them a little help. But they'll still feel epic.
Overall great job for a first time!