which is 100% skill based is chess and there is a website velocitychess.com where you can play chess with bitcoins too, was playing here two years ago, haven't visited this website since then.
about chessvelocitychessThere was actually , they didn't accept bitcoin , they had just deposit and cashout with paypal , i played there for some time (cashout minimum was about 50$)
had in-game currency that you could earn in tournaments and single games , i reached cashout and never get paid , that was complete scam , you can read more in the web about velocity.
chesscubeThe best chess for money was (chesscube) , had in-game currency you could cashout (had many grandmasters there )
they shut down money-part (2013) because of cheating but site still alive and solid to play for fun and training.
playchessbest client for pro players , every champ played/ing there (realy solid)
has in game currency called (ducat) , AFAIK you cant trade ducats for money but u can buy account serial number and chessbase.com softwares and Educational films with them .
LichessRealy good one , first free-software chess , they support many variants of chess are realy fun.
Time to time there is tournaments with cash prize.
carlsen plays there sometimes.
Thx OP for Starting Topic , I'm Looking for skill based games too.