What is Vincent's and his brother's favorite game in the movie 'Gattaca'?

Vincent and Anton love playing Chicken, the game where they both swim from shore far out to sea. The first to get scared and swim back would be the loser.

Anton always won because Vincent's born an in-Valid, but the last two games they played, Vincent beated Anton because Vincent didn't save any energy left for the swim back. When Anton drowns, Vincent saves him and swims back to shore.