People in the community can mod in new materials and reactions, but not much else. qswitched can work on those, or on UI / gameplay / new module types / etc.
I agree qswitched should not spend their limited time on creating new materials, and I'm not a fan of the format of this thread, but I'm all for people modding in new stuff that they like, even if I won't use it.
EXTERNAL ATTACHMENT BOLTS (for launching missiles/drones in low numbers)
FREE ELECTRON LASERS.
LIQUID DROPLET RADIATORS.
TELLER ULAM DEVICES.
And that's just off the top of my head. My god, the list of things I want to be added to the game is freaking huuugeee.
... you know what, I want a (pseudo-) scripting language to code up our own modules, along with examples on how the existing modules would be implemented there. This would allow us to mod in this stuff, assuming there are people who know or can learn enough about them in the community.
Decompressing the main cabin, then repressurizing from a liquid oxygen tank, all heated up by crew member metabolism
You could asparagus stage the machineguns to get past the 250 ammo limit.
Depressurizing by LOX heated by the cabin's latent heat isn't too dangerous as long as you keep the partial pressure low and measure the LOX injection so you don't add too much. This assumes the crew is in space suits and doesn't mind waiting. Remember it is the partial pressure of oxygen that is important not the actual air pressure.
Even true for humans where you can survive in an extremely low pressure environment as long as your air is 100% Oxygen. From the top of my head it is on the order of 2.5lbs PSI. Just make sure you're acclimatized to avoid the bends.
An extremely unsafe and hilariously impractical propellant?
How about Cyanogen Azide/Liquid Flourine bipropellant? We all know about how horrible LF2 is. Cyanogen Azide (CN4) is described by Derek Lowe as "a colorless oil which detonates with great violence when subjected to mild mechanical, thermal, or electrical shock". Because it's a liquid we could actually implement it as an in-game fuel...
We dig deep down into the very building blocks of life, seeking to twist them to our will. We destroy mass itself to turn its energy to our ends. The speed and intelligence of our machines grows without bound. But even the power of gods isn't enough. Ever hungry, we turn our eyes to the stars...
I sure hope there's someone else more advanced out there. If we're the first, the universe is screwed.