I know the point is hacks and stuff that push the hardware or overcome limitations, etc.. But the thread also has taken a turn of, I can't believe I did that on an Amiga (or something like that).
I used to play Nettrek, via SLIP, on an Amiga 500. I was amazed that it worked, having both the TCP/IP stack running and having Nettrek play perfectly fine without much lag. It was also in color, had bitmaps, a few other graphical bits, big display, sound -- and you could have it speak chat messages. (This was a game that relied HEAVILY on communication, and was fast-paced.. Hearing your teammates was a huge boon.)
I had first played it at college on a Unix mainframe with a T1... and playing it on the Amiga, even with just a modem, blew it away.
(Having said all that, it took AGES to get it to work at first.. Working on the startup-sequence, settings, etc etc, but once I got it going, it was solid.)