The one big payday was from a PC games publisher (SofSource). Their business model was to license select shareware and publish it commercially. The published games were displayed on racks in stores like Sears, positioned as impulse buys.
To kick off their Mac line SofSource licensed both my games, plus two others (Diamonds 3D was one I think). Unfortunately Sears and maybe others decided not to carry the Mac line. SofSource lost money and got out but I got to keep the advance. I still have some boxed copies the publisher sent me, plus a couple I bought at CompUSA as a lark.
I was contacted by other publishers too but most seemed very shady. SofSource seemed to go out of their way to treat developers fairly (we kept the rights to our games and could even keep selling them as shareware.) I was sad the Mac line didn't work out for them.