Choose how many laps, choose a horse, choose a stake, and start the race. Four runners, white, blue, green and brown, and a result board that fills in as they cross. Winning pays, losing does not, and the balance in the corner is the entire progression.
It is honest about being a coin flip with a run up, and the fun is in the run up: watching a horse you did not back come round the outside is a specific feeling that no amount of statistics would improve. A round is ninety seconds. A hundred pounds is about ten rounds if you are careless and considerably more if you are not.