with regards to feasibility, this would be a straight port of the unique gases from tg and presumeably not an overhaul to the main atmos code, so wouldn't be as hard to implement (although i'm not a coder so i may be wrong.) In terms of balanncing this wouldn't have a massive impact as you'd need to be a fairly competent atmos tech to create mixes like stimulun and it'd take a while to prepare as well as making others in atmos suspicious. Tritium also requires some setup to produce in large quantities, so it wouldn't have an early round impact in the case of antags. Atmos technician currently lacks flavour and is often left unloved, justice for atmosia!