|Discontinued due to legal threats and incessant user demand
|Google Code (Archived) (leaked)
Backup from archive.org
The Nintendo 64 was only about three years old at the time of UltraHLE's release. While there were earlier projects aiming to emulate the console's inner workings, UltraHLE was the first to run games at a playable speed on a typical Pentium II/III system with a decent GPU. In contrast to 8 and 16-bit emulators which concentrated on simulating operations at a lower level (although they too, like NESticle and ZSNES, resort to game-specific hacks and other shortcuts for games to be playable on modest hardware), co-authors Epsilon and RealityMan took a different approach through intercepting C calls and using libraries to respond to them. This also led to a strange situation, especially with later NES/SNES emulators, wherein emulating the Nintendo 64 would at the very least call for similar if not lower-end hardware compared to emulating an early console in an accurate fashion.
UltraHLE also used the Glide API, which has since fallen out of use due to being specific to 3dfx adapters. Due to its popularity, several Glide to DirectX translation utilities were made specifically for UltraHLE for non-3dfx video cards.
As it was released at the time when the console was still on the market and considered profitable, Nintendo threatened the authors with legal action. This, along with pressure from users who constantly pestered the developers for new features and such, led to Epsilon and RealityMan discontinuing the emulator.
Despite being a proprietary emulator, the source code leaked in 2002 which provided some insight into how the emulator worked. This was used as the basis for an OpenGL port of the emulator called UltraHLE 2064, but by this time newer, better emulators were already available. The source code was also briefly updated as UltraHLE Alpha, which was later incorporated into Surreal64 for the Xbox.
Other than being of historical value and for the distinction of trolling Nintendo while they were still marketing the console, users are generally better off with newer emulators due to its limited compatibility and dependence on the Glide API.