The 2nd Annual Ellington Bid-Tac-Toe Challenge is a competitive programming challenge designed to stimulate multiple-level thinking in a competitive game with intuitive rules but without dominant strategies. The challenge was opened to three schools recognized for their strong programming culture: MIT, Caltech, and Carnegie Mellon. A total of 27 people entered under 19 team submissions.

The game is a variant of the game tic-tac-toe where the players simultaneously "bid" points on each square to claim them instead of taking squares in turn. The winner is the player with the most number of "three-in-a-row" after each square has been claimed.. This adds several layers of complexity in creating strategy with a limited number of points the players have to balance their aggression in getting squares.. Also, a large measure of success may rest on each algorithm's ability to recognize and create counter-strategies instantly against other strategies.

On November, 2007, Ellington happily announced the winners of the 2nd Annual Ellington Bid-Tac-Toe Challenge. The final winner from Carnegie Mellon is Brian Ziebart., who is currently pursuing a PHD degree in Machine Learning. He received a prize of $1,500 and after beating the two finalist winners from MIT and Caltech, Brian won the $1,000 GRAND Prize.