Escrow service for chess players to play against each other for price money deriving from the 2 players.
Player 1 and Player 2 will arrange a match and stipulate the rules as well as each players contribution. The winner takes all less 7.5% Commision.
And how do you plan to prevent cheating? Nowadays, with advanced tools so easily available, it is almost impossible to even detect cheating, let alone prevent it.