The origin story of Rust is classic: they got tired of Day Z and wanted to make it better, so they hired some random contractor to copy Day Z with elements of Fortnite and Minecraft, the developer complains that he's entitled to more money from the success of the game, lawsuit follows, and then Facepunch supposedly claims the original version was so buggy they have to rewrite the whole thing from scratch. Unclear if they were just trying to start fresh so the lawsuit wouldn't follow them forever, but it started out as just a clone of another game and they turned it into a hugely successful business (and an incredible game). Most games have a short shelf life, but I've watched at least over the past 4-ish years, and the rate that they continue to push changes is impressive.