Not the same but the xbox app has a surprise me button which picks a game for you to play next.
Steam shows you games similar to what you play?
Where? I've only ever seen it on store and even then its a bit hit and miss IMO
I just have these bookmarked and get whatever I fancy that's on offer:
https://store.steampowered.com/search/?maxprice=20&category1=998&category3=2&specials=1
https://www.fanatical.com/
Sorry guys I was meaning more from my own library, I did find a site earlier tho thats helped a bit
Thanks mate, I'll have a lookSteam Labs has a way to narrow down your search, found a few games that way that I wouldn't normally look at.