UltraHLE came out in 1999 and it was mind blowing out of nowhere at the time. I was on IRC at the time neck deep into the whole emulation thing on the NES more than I'd want to admit with things, and when it dropped people flipped out. People split into two camps of warez that shit, and the others who would ban people on sight for asking for N64 games (which is ultimately what happened for a good stretch) as it was straight up warez and Nintendo was and always have been dicks about piracy. The unique thing with this is that it's a high level emulation program, it doesn't shoot for accuracy in the least bit and uses any cheat in the book to halfassedly get things going at amazing speeds on hardware that should just suck hard with it and in general not function at all. In that year I was rolling with a Celeron 466 machine with not that much ram and a middle of the road video card and I could play Mario, Wave Race, Zelda, Bomberman and some others in high resolution (640x480) visuals and the audio was pretty damn stable and sounding right too.
It's a cheat though when you go that way you throw a lot under the bus with assumptions on how stuff works and you throw variables at the wall and see what sticks or not on what functions. It only had that one release yet a community popped up that kept updating the initialization files for it as it allowed more and more games that didn't work in the stock release to work and in some cases be fully playable.
You can read up on the technical info of it at the original emulators release site which is amazingly still online.
http://www.emuunlim.com/UltraHLE/main.htm