jmLÇChainBet is a proposed Bitcoin Cash protocol to enable on-chain betting, but it looks like a bit too complicated. Wish memo could have built-in feature for this.
https://github.com/fyookball/ChainBet
https://whatsonchain.com/tx/169f78f72a82458b12c8291d086b0daabc1e0be3d66e1630e28b7e164ceed763