One way to get noticed is not with mechanics per se, but with theme and art style. Looking at the OSR, products that stand out evince a clear and original creative vision: Mork Borg, Ultraviolet Grasslands, Mothership, and Mausritter all communicate their theme very clearly. Some of those has quite innovative mechanics, but others do not. Indie games like The Between or Thirsty Sword Lesbians meanwhile, are very thematically focused.
In a way, that's what White Wolf did in the 90s to stand out. By contrast, one criticism I have with 5e third party products is that they sometimes stick too closely to the house style. This is more than just style of the artwork, but also the fonts, layout, and use of those transparent backsplashes behind art pieces. It's also in the phrasing of section headers or monster abilities. Perhaps this is because the audience is familiar with that style...and probably if you stray too far away from it you might end up confusing people that are used to 5e (for example, if these 5e clones use conditions with same or similar names to 5e conditions, that's going to get confusing).
