Rules

Battlesnake Blackout is a grid-based multiplayer game in which each participant controls a snake. The goal is to be the last snake standing.

Basic Mechanics

At each game step, all snakes simultaneously choose one of four moves: up, down, left, or right. The total round trip from our server sending the game state to receiving the move response must complete within 500 ms. Network latency counts toward this budget, so participants should account for round trip time when designing their agents.

Health & Food

Every snake has a health counter that decreases by one each turn. A snake dies when its health reaches zero, which happens after 100 turns without eating. Food spawns randomly on the board. When a snake moves onto a food tile it:

• Restores its health to full (100), and
• Grows by one tile in length.

Elimination

A snake is eliminated if any of the following occur:

• Wall collision: the snake moves outside the boundary of the board.
• Body collision: the snake moves into its own body or the body of another snake.
• Head-to-head collision: two snakes collide head-on. The shorter snake is eliminated. If both snakes are the same length, both are eliminated.
• Starvation: the snake's health reaches zero.

Fog of War

Unlike standard Battlesnake, Battlesnake Blackout uses imperfect information. Each agent only perceives the area within 5 tiles of its own snake's head. Opponent snake segments outside this radius are hidden. Food is an exception: on the turn it spawns, it is visible anywhere on the map regardless of distance. From the following turn onward, it is hidden again unless it falls within the 5-tile view radius. This requires participants to develop strategies that account for hidden opponents, including opponent modeling, trap setting, and long-term planning under uncertainty.

Submission

Participants host their own web server that receives the current game state as a JSON request and responds with the chosen move. This approach allows complete freedom of programming language, hardware, and algorithms. See the API documentation and Tutorials for implementation details.

Tournament

Until the start of the tournament, participants can test their snake in an online leaderboard. This leaderboard is solely for testing and does not have any effect on the outcome of the tournament. However, we highly encourage players to participate because this is an important opportunity to find flaws in their own implementation.

During the tournament, snakes will participate in free-for-all games consisting of four players. The winner of a game receives two points, the second place one point, third and fourth place no points. The average score across the tournament games (as said before excluding daily test games) determines the final ranking among participants. Only participants beating the baseline agents in this evaluation are eligible for prizes. If less than five participants are eligible for prize distribution, no prize money is distributed. If more than 12 participants are eligible, a second round of tournament games will be played among these 12 participants. In this case, the ranking among the top 12 participants is only determined by the average score between these 12 participants (previous evaluation games among all participants are not counted to exclude very weak enemies).