Bethesda has confirmed that the previously-detailed DOOM Classic and DOOM II patches are now available. The patches for both games aim to improve in-game lighting and audio to match the originals, as well as add game performance improvements. On top of that, linking your Slayers Club account in-game will earn you unique skins for use in DOOM Eternal at launch.
DOOM Classic and DOOM II update available, includes audio, performance, and lighting improvements, DOOM Eternal skins bonus detailed
The way they were meant to be experienced