Halite is an artificial intelligence programming challenge, created by Two Sigma, where players build bots using the coding language of their choice to battle on a two-dimensional virtual board.

This year’s challenge, Halite II, had a space theme, where players’ bots control ships that mine planets to grow their fleets and defeat their opponents. Learn to play Halite II here.

The Halite competition is a fun way to learn and apply AI, machine learning, and other advanced algorithms by writing smart bots in a collaborative, challenging game setting. Designed for coding enthusiasts of all levels of experience and open to the public, Halite has created an engaging game environment to learn, write, and visualize code in action. Halite was created as a Two Sigma open source project for community outreach and education.

The 2017-2018 season ran October- January, with participants able to join up until the last week of the competition. Players submitted bots that play games against other bots until the Halite ranking algorithm determines a player rank. After submissions were complete, a winner was determined through a week of final matches.

The general who wins the battle makes many calculations in his temple before the battle is fought

– Sun Tzu


Halite I was conceived of and developed by Benjamin Spector and Michael Truell in 2016. Two Sigma, having had a history of playful programming challenges for its mathematical and software-oriented teams (e.g., see the Robotic Air Hockey Competition) retained Ben and Michael as 2016 summer interns to develop Halite, run an internal Halite Challenge, and ultimately open Halite up to human and non-human coding enthusiasts worldwide. Halite I was a great success, developing a flourishing community of bot builders from around the globe, representing 35+ universities and 20+ organizations.

As a result of the community’s enthusiasm, the Two Sigma team decided to create Halite II, an iteration of the original game with new rules but a similar structure and philosophy. With Ben and Michael as creative advisors, Halite II was developed by David Li, Jaques Clapauch, Harikrishna Menon, Julia Kastner as an evolution of Halite I. The team considered simply reviving Halite I, but given the progress the community made and the number of open source bots that had been published, the team decided to create Halite II with new game mechanics and a fun background story that fleshes out the Halite universe. Halite involved moving pieces around a board with only up-down-left-right options. In 2017’s Halite II, bots battle for control of a virtual continuous universe, where ships mine planets to grow larger fleets and defeat their opponents.

In last year’s game, many bots were built with Machine Learning techniques, but to further encourage the community to explore deep learning, reinforcement learning, and other techniques, the Two Sigma team, along with support from Google Cloud, will sponsor GPU usage for qualified players. In addition, the Two Sigma Deep Learning team has put together an ML starter bot to help competitors get started on ML

Successful players will win based on the relative sophistication of their code as well as their gaming strategies. The best tactics for Halite II will require the use of sophisticated pathfinding, using concepts such as Prim’s and Dijkstra’s algorithms and the Traveling Salesman Problem.


Halite II was built with an initial set of coding languages but the community is encouraged to also write their own starter kits in their languages of choice (learn more about making a kit). Players can download a starter bot, try out one of our tutorials to make updates to the bot, and/or improve the bot on their own. The Halite team has made a number of helper methods that can allow a beginner to jump right in, but we expect more sophisticated players to try Machine Learning and other sophisticated AI techniques.

As users improve and re-submit their bots, they should see their rankings on the leaderboard change. Players can also join one of many private or public hackathons to see how they compare to their peers, and even create custom leaderboards to see how their rank compares to friends, classmates, or colleagues over time.

Halite I was especially successful because of its robust forum community. Any player, from beginner to advanced, can join a forum to ask questions or learn best practices, besides making some online friends.


To help productize and orchestrate the public launch, Two Sigma reached out to Cornell Tech, a leader in graduate tech education. With a shared interest in encouraging programming, entrepreneurship, and growth of the thriving New York tech scene, the two partners initiated the public Halite competition in November 2016. Cornell Tech is providing ongoing game support and community management, and by working closely with the online gaming community, it will empower players to collaborate, learn and have fun. Additional partners have since joined the efforts to make programming more fun. This year, as part of Product Studio, a group of Cornell Tech masters students are building “Halite for Kids”, a version of Halite that can be taught in middle schools.


Many have contributed to Halite since Ben and Michael’s invention; in addition to the Halite II core team (David Li, Jaques Clapauch, Harikrishna Menon, and Julia Kastner), there were many other major contributors to Halite II.

Two Sigma Contributors:

Camille Fournier, Alfred Spector, Serguei Narojnyi, Xinyun Wu, Barbara Zhan, Georgi Georgiev, Jason Zhang, Nick Vrilo, Tuan Anh Hoang-Vu, Scott Rich, Paul Butler, Scott Lynch, Nick Golubyev, and many more who gave feedback during our internal competition.

External and Community Contributors:

Special thanks to Arnaud Sahuguet, Erik Wickerman, Raymond Shumm, Nick Malaguti, Mike Chase and Arjun Viswanathan, as well as to all the users who provided questions and comments to the forums and other conversations with the Halite Team. And thanks to the ~100 players who made contributions to the open-source Halite II project over the course of the 2017-2018 competition.

And our greatest appreciation goes to Janzert, who made the most Github commits of any community contributor (non Two Sigma employee), with 141 commits over the course of Halite II. We are so grateful.

May the best bot win!