I know they didn't actually run on "Ultra 64" hardware (most definitely because that hardware was nowhere near ready when those games were made), just that they had the logos. Wasn't the Dreamcast also known as "Sega 64" at some point? I remember seeing that in some gaming mag around '97..it was obviously very early in the DC's development when they didn't even know whether the American or Japanese design would be used.
As far as I can remember from various moments of curiosity throughout the years: HVC - Home Video Computer - Famicom NES - Nintendo Entertainment System SHVC - Super Home Video Computer - Super Famicom SNS - Super Nintendo Entertainment System NUS - Nintendo Ultra Sixty-four - Nintendo 64 DOL - Dolphin - Nintendo Gamecube RVL - Revolution - Nintendo Wii DMG - Dot Matrix Game - Nintendo GameBoy MGB - Mini GameBoy - GameBoy Light/GameBoy Pocket CGB - Color GameBoy VUE - Virtual Utopia Experience - VirtualBoy AGB - Advance GameBoy - GameBoy Advance AGS - Advance GameBoy Special - GameBoy Advance SP NTR - Nitro - Nintendo DS OXY - Oxygen(?) - GameBoy Micro USG - ??? - Nintendo DS Lite TWL - ??? - Nintendo DSi These are all I can remember, if anyone knows of any others or can fill in any of the ??? that'd be great. Some of these may be wrong, from memory most of the information came from here.
Er... it did? Only Killer Instinct was revamped due to the release of Killer Instinct 2 before the Nintendo 64 was (finally) released.
Small info on DS. It's actual original code name was Iris and original plans were a Single Screen Unit (esentualy a GBA with a 3D processor). They morphed that idea by throwing on a 2nd screen & an additional 2D processor (identical to the first which are base on the gba) and changed the code name to Nitro. God I should have hid that TEG board under my desk. =(
One other possible name for the Dreamcast was "Guppy". Apparently that name got first place in a poll conducted by SOJ, and "Guppy" was silkscreened on the first Japanese prototype PCBs, before Katana. BTW, I'm serious - this is not an April Fools joke.
There was an interview a few years back where someome from Sega confirmed that Guppy had indeed been selected in a poll before Dreamcast was ultimately chosen, though I've only just noticed the VM having a "Potato chip" inside - how did I miss this one for so long?!