The rating was posted by the European game rating authority PEGI and spotted by Gematsu on Twitter (before being picked up by VGC).
The listing describes the new release as "a PC port of the original Resident Evil game (1996)" and has a PEGI-18 rating for "depictions of graphic violence to human characters" and "intense and sustained horror sequences".
Resident Evil was previously released on PCs in Japan in December 1996 and 1997 in North America and Europe but currently isn't offered on Steam.
It also isn't widely available on other modern storefronts either, with the only way to buy the game on current-gen systems being the PlayStation Plus classics version, which is based on the 1997 Director's Cut.
A rerelease of the original game would therefore be a pretty welcome development, but it remains to be seen what other platforms this will reissue will come to. We'll try to keep you posted as more information becomes available.