We should have more rules on what defines a 100%. Is it all of the collectibles, plus story? Or is it all of the achievemrnts. And is there actually a way to restart collectible progress to do a "run?"
Also, we should add another tab for legendary difficulty. I'd be happy to run it
Go to My Games & Apps, click option button aka start button on controller when you're hovered over Ryse, click on Manage Game option that pops up, should show you the game, addons if you have any, and your saves. Just delete the save. This erases all progress. Fyi. But you can start fresh.
Go to files C:drive: ProgramFiles(x86)/steam/steamapps/common/Ryse Son of Rome and delete the file. You will then have to reinstall Ryse, and everything should be reset except for achievments as that is Steam not the games local files