Choose the winner of each game, either straight up or against the spread. Win by having the most correct picks.
Use a sportsbook format. Start with a number of shares and choose how many to wager per pick. Win by having the most shares.
Pick one team to win each week. Pick wrong and you lose. Win by surviving the most weeks.
Similar to Survivor, but only for a single week. Picks are required any day there is a game, and contest organizers choose what games can be chosen from.