Imun's past is shrouded in much mystery. While most of the gods squabble over who gets what dimension and try to get the mortals to worship them, Imun simply wanders the dimensions, quietly playing chess with a grandmaster over here, or playing virtual reality games over there.
Imun travels quite a bit. There are very few gods who don't know him. He always disguises himself when amongst mortals so there aren't even any myths about him among the mortals except for his personal favorite race, the Ilosa.
One of the biggest mysteries about Imun is how old he is. The eldest of the gods can remember him predating even them. As he seems uninterested about the politics of the gods most just see him as a constant of the gods. A nice person to have as a friend, but not very helpful in a fight against another god.
Most gods are very friendly with him. As Imun isn't anyone's enemy he is always welcome to any pantheon of the gods. Quite a few gods get him to quietly help their priests with planning a festival. He's always the one who can pull out something to pass the time or lighten the mood. And there is no better person in the cosmos to help one out in a competition against a mortal. He refuses to help against other gods though.
Sometimes he creates his own games. They're usually video-games but some of the elder gods can remember the time he came up with a game that was played on a board. That one was a role-playing game where you crafted pieces and moved them around on a board that looked like a model of a planet. The god who won that game is now commonly known as the most powerful god. Coincidence? Maybe, but that god always seems to have extraordinary luck when it comes to getting his way.
It seems that recently Imun has been traveling around dimensions a bit less than normal and has been gathering his most trusted friends from among the Ilosa to assist in a project off in a dimensional corner.