I have two ideas, I reckon the second is a bit far fetched.
How about we create paid wager races/tournaments, where ducklings compete against each other and get multiple times the reward (the pot), as the game is not free. The race could automotically start as soons as an X number of ducklings have paid for their seats and ready to play.
my second idea is the following:
Imagine playing poker and dice... raising bets or bluffing other players as in poker!! How about we create tables like in poker, and players compete against each other for the pot (1v1 up to 1v6). The objective is to be as close as possible to the the target(s) drawn randomly like in the lottery. The numbers could be classic x2 dice 1 to 6 to render the experience more userfriendly