New guns and exposion sounds?

These would indeed make nice weapon sounds!
The biggest problem i see is the inherent reverb and the resulting (overall) thin high end, but that could probably be worked around. Adding a bit of robot-ish high end noise shouldn't be too hard.

Out of curiosity, what did you use for recording? Edit: Nevermind, it's noted in the sound descriptions.

I'll look into incorporating these at some point if I find a reasonable application.

Other people may want to weigh in here but I think we are avoiding CC Attribution licenses because Linux distributors are pedantic. I may be recalling this wrong but apparently if some game with a CC Attribution license is included in a Linux distribution then the distributors feel the need to attribute all the contributors to the game (rather than, say, linking to the credits for the game). This bloats the license for the distribution so the distributors avoid adding things with these license types.

When sourcing our sounds I made sure to avoid these licenses. I am not sure if this is still a concern or whether other content for the game is even compliant anymore. But to be safe you could re-license these for us.

I can alter these sounds and add some futuristic elements or change frequency balance. Shortening the reverb tail is also possible, however this is what makes them so powerful in my opinion. Most of this sound is the amazing impulse response of the environment. Also I can make several versions for distant sounds (to make it sound like heard from another side of the map). Here's a pack of energy weapon sounds I made with pure synthesis:
http://www.freesound.org/people/unfa/sounds/187119/
And some synthetic explosions:
http://www.freesound.org/people/unfa/sounds/189779/
http://www.freesound.org/people/unfa/sounds/156500/

Yes, I can release these under GPL for the game, I own these recordings.

I really like that laser sound. I think the problem with the explosions is that they don't sound explosive enough. They are too low pitched and need to be "sharper" IMO.

I've used one of those sounds for sonic blaster impact, since that weapon now appears widely available.

Can it be assumed to be GPL?