See the dev team's opinions on this. Beyond this, there are three more important issues:

1) The fmod sound library that verge uses for all sound and music (and is required for verge.exe to run) is free only for non-commercial use. Before even thinking about selling anything you'd need the $100 for a fmod shareware licence.

2) It's quite common to use ripped material from other games, or material found floating around the internet. If you plan to sell anything, you'll need to be completely sure that everything you use is free from copyright, and permission is granted for commercial use.

3) Many widely used graphics and sound file formats that verge supports are somewhat murky in copyright terms. In particular, avoid jpeg, gif, and mp3 formats.