If you obtained the game for free before it had gone paid you might have noticed that the game has uninstalled itself and isn't installing anything if you try, here's why:
When 0.9.4 released last week an exploit in Steam was discovered, I won't be providing details on the exploit itself for obvious reasons. However, the result of this exploit allows anybody to activate a free copy of BallisticNG officially through Steam. This shouldn't be a problem, but over half of all game copies are being obtained through this method and on 0.9.4s release alone 99% of all copies from that day came from this exploit. Because the game is now paid this is effectively piracy, this wouldn't be a concern if it wasn't happening through the store front the game's being sold on.
Do not attempt this exploit, you will only end up with an empty game in your library!
Because of this I have temporarily pulled the free copies contents from Steam. I contacted Valve last week to query and let them know about this issue but they haven't got back yet, this a critical issue that free players need to be aware of so I needed to post ahead of them responding. It is currently unknown when Valve will get back and what the result is going to be, but if you're a free player the only way to play the game right now is to unfortunately deactivate the free license from your account and buy it.
Apologies to the free players this affects, I'm hoping this can be resolved soon. I will be posting about any further developments of this situation when I'm able to.