Spoilers for Requiem follow.
Resident Evil Requiem is a whistle-stop tour through 30 years of the franchise's history, with the adopted child of Outbreak's own Alyssa Ashcroft venturing to Raccoon City and the RCPD alongside a Wesker clone, while Leon contends with Mr X, Plant 43, a giant spider, a new Nemesis, and even someone who appears to be Hunk, all culminating in the reveal that Oswall E. Spencer regretted everything and wanted to make amends.
However, according to reputable leaker Dusk Golem (who first broke that Leon Kennedy was returning), Capcom originally planned to go even further back.
"I never said this publicly (& glad I didn't as people might be trying to execute me if I did), but I am aware they did work on a return to the RE1 Mansion that's just not in the final game," Dusk Golem said.
Mr X, Wesker clones, and even a new Nemesis all make sense — they can be reproduced. We've seen tanks full of tyrants and other Umbrella experiments. Even the return of Raccoon City works because the Resident Evil 3 remake retconned the explosion, ensuring that the RCPD and other landmarks survived the blast. But I can't...
