Sure thing!

1. Most of it has been me toiling alone, but recently I've been joined by a full time QA person (Jonathan Palen) as well. In addition to that two other people have done some part time work: Dana Nelson has been instrumental in designing the difficulty curve for Endless Mode and many of the funniest commentator lines are written by Albert Lai.
2. I use Unity. Voxel models designed in Qubicle and Magicavoxel. Voice Audio generated by the Mac command line.
3. The idea sprung out of a tech exploration, while I was taking a break from another project. I'd been working a lot with voxels, so I was curious if I could dynamically cut them with a sword. The format of the commentators talking about you rather than to you came from a little prototype I built for the last Global Game Jam:

Everyone who have bought it here will get a Steam key. You will not need to buy it again.