Official answer: You retain all rights to your game. Anything you submit to us will only be used to be added to Armor; we won't redistribute it or claim any ownership of it.
In reality, if you upload a game through /submit and don't tell someone about it (likely me)... it's 99.99% likely to never be touched. Basically every game we add is a game where we've spoken directly with the developer, requested that we want the game on Armor, and worked with the developer to get the game onto Armor.
Also, you should only upload games through /submit that YOU own the copyright to. Don't be uploading other people's games... it creates problems for us from time to time (small ones, but still.).
If you have any other questions concerning getting a game you made onto Armor, you can email me directly at tasselfoot@armorgames.com. I will be completely honest with you about your game. :)
-Tass