Came across this quote, regarding the hidden version of Tempest 2000 in Tempest X for the PlayStation 1:
"I guess I feel safe sharing this 21 years after release:
The hidden 2000 mode wasn't supposed to be there.
Several of the higher ups involved mandated a lot of changes in the "X" mode that I didn't agree with. I didn't think they understood the beauty of Theurer's or Minter's versions of the game. I thought they were ruining it by putting their thumbprints on it with the bitmap monsters, Helvetica font, etc.
I nearly lost my job over hiding the 2000 and Plus modes in there. Many key people didn't know about it until after the game had already hit the presses. But I'm glad I did.
It's fun to see people still play the game. It was a lot of fun working with N on this. We also did Saturn and Mac Classic versions that were straight up Tempest 2000 ports. We also prototyped an M2 version just for fun. That never shipped."