A discussion of infravision and how various players implement it is happening over at the Goblinoid Games forum. Some use it straight by the book (thermal-ish Predatorvision). Some use something similar to today’s night vision goggles, complete with greenish tint. Some just sort of handwave “seeing in the dark” and leave it at that.
I used to do the latter, but lately I don’t even use irfanvision. PCs cannot see in the dark. Many monsters can see in the dark, some of them well and some only a little.
My thinking is that none of the games attempt to define how a normal cat, for instance, sees in the dark. I more or less treat many monsters like that. The pseudo-scientificish thermal vision explanations don’t do anything for me.
Our homebrew Wizards & Warriors game, with only human PCs, doesn’t even mention it, though there are cat’s eyes and rat’s eyes magic spells.
On another note, a while back I noted that I was making writing some game projects priorities and would be devoting more time to writing and gaming. Didn’t happen. I’m struggling to get back on track, but it looks shaky for the near future. Hopefully I can get my kobolds in a row.