If it requires a vacuum mode, then there will be a lot more coding needed. That means you need one Oxygen atom to turn to fire. Meaning, you'd need the ENTIRE space filled with Oxygen. You'll probably end up with 5 fps in the end.
So therefor, TPT was not built to be fully realistic.
No, it's not.
Three words: Novel,but useless.
Didn't you read the guidelines? Just because it's not realistic doesn't mean you have to add it.
O.K. Back in the 18 century scientists didn't know what oxygen was. They thought it was some sort of other weird gas called phlogiston that was emitted by fire. Hey, that could be an element. That is sort of how Powder Toy air works. It is just normal air but all mixed together, and you can't separate it's parts, or tell what's in it. Therefore, we don't know if it has oxygen or phlogiston. When you add oxygen, you are simpley tracking those new oxygen molocules. The rest are hidden if there are any.
Phlogiston
Name:PLGN
Type: Gas
Color: similar to smoke
properties: stops all reactions (fire, explosions, rust)
(actually, I might post a legitamate thread, imaginary gas = useful)
Back to the original suggestion, wouldn't it also be possible to simply have a setting which sets the default air pressure to -256 or so?