Doom 64 is now a pre-order bonus on all platforms.
DOOM Eternal

Those looking forward to DOOM Eternal in November will have to wait a bit longer now. id Software announced today that DOOM Eternal has been delayed until March 20, 2020. However, as a bit of good news amongst the sadness is the fact that they will now include DOOM 64 as a pre-order bonus on all platforms.

Previously, DOOM 64 was announced only for the Nintendo Switch. However, this change means that we will now see DOOM 64 on the Xbox One, PlayStation 4, and PC in addition to the Switch release. Unfortunately, DOOM 64 also won't be released until DOOM Eternal is released. This means that both DOOM Eternal and Doom 64 will be out on March 20, 2020.

id Software says that they want to deliver the best experience and "for DOOM Eternal to live up to (their) standards of speed and polish" they made the choice to delay it a few months.

It seems as though the studio has run into some issues with the game's Invasion Mode. id says that they will release this mode at a later date after the game's launch in March. Invasion Mode is the game made that will allow you to enter into another player's game as a playable demon.