Multi-agent reinforcement learning competition

Reapers of Acheron

The dead are waiting. Your rivals aren’t.

Descend into Acheron
03 Bot slots per competitor 04 Bots per match 500 Turns 04 Stone Docks 09 Soul Wells

Prologue

The River That Remembered

Souls enter the underworld along the black currents of Acheron. Without guidance, they drift into deep fissures and vanish before reaching the realm of Hades.

Nine Soul Wells mark the river in staggered ranks of five and four. Empty tiles regrow souls as long as nearby souls remain. Stripping a Well completely silences it for the rest of the match.

The Decree of Hades

Hades needs a Reaper. Make it yours.

Four Stone Docks stand along the southern shore. Souls delivered across Acheron are banked at these docks to tally your tribute. Each trial pits four bots against each other for 500 turns.

Speed alone will not win. You must balance fast collection, sustainable harvesting, and rival defense.

Meet the competition
Read the whole prologue

The River That Remembered

The Source and the Living Beacons

Before the dead had names for the places they feared, there was the Source. From it, souls entered the dark country beneath the world and found themselves upon the current of Acheron. The river carried them through caverns of black stone toward the dominion of Hades, but it did not promise that every soul would find the way.

Acheron divided beneath the earth. Its currents slipped into fissures, descended through unseen channels, and disappeared into depths from which no ordinary passage returned. Newly arrived souls did not know which current would lead them onward. They drifted, gathered, separated, and vanished from the passable channel altogether.

The Soul Wells were the answer the Underworld grew for itself. Nine of them mark the trial waters, arranged across the river in staggered ranks of five and four. Each Well spreads across five shallow places: a central hollow and four arms extending from it, like a cross laid upon the dark river. Souls drawn to the confluence settle into those shallows, one to a tile, until five gather beneath its surface to reach saturation.

A Well with only one soul gives off the faintest call. With each soul that joins it, the call strengthens, and other wandering souls are drawn in more readily from the Source to replenish empty shallows. Yet this living beacon carries an irreversible danger. If a hunter takes the final soul from a Well, the confluence loses the vital presence that held its beacon alight. For the remainder of that five hundred turn match, it will gather no more.

The loss is not the destruction of the souls that were carried away. It is the permanent loss of a path. Those who arrive after a Well has gone dark drift past the dead shallows and descend into the deep channels, beyond the reach of the hunters and the passage to Hades. The river still flows, but it becomes worse at bringing the dead where they need to go. To harvest with restraint keeps the guides alive. To empty a Well entirely silences a beacon for everyone who comes after.

The Decree of Hades

The Sovereign and the Four Hunters

For ages, Hades received the dead along the southern shore. Four monumental Stone Docks stand there, set apart from the vessels' launch berths and facing the long reach of the trial waters. At those docks, souls carried across Acheron are received into his kingdom and tallied into each hunter's banked tribute.

Yet the river required more guidance than one sovereign could provide. Too many souls arrived confused; too many slipped away into the unmapped channels. Hades needed a Reaper: not merely a gatherer of spirits, but an autonomous vessel capable of traversing Acheron, collecting the lost, defending a course, and delivering those in its care.

So he called four hunters to the river and granted each a vessel with cargo capacity for three souls. Their trial lasts exactly five hundred turns. Vessels move across the shallows to take souls aboard automatically, then race south to unload at any open Stone Dock. Hunters may also loose the spectral Wraith Chain across the water, banishing a rival back to the depths to buy vital seconds while leaving the rival's cargo intact.

When the final turn concludes, the hunter who delivered the greatest tribute will be named Reaper of Acheron, with carried cargo and banishment resilience deciding any ties. Hades offered no further explanation of what he expected to learn. He had not summoned them only to watch how much they could carry. He wanted to see what each would choose when the same task placed speed, restraint, safety, and advantage in conflict. He would let the river reveal what their algorithms concealed.

Four ancient archetypes already haunt the waters: greedy collection that strips the nearest Well, sustainable stewardship that protects cluster beacons, aggressive denial that hunts with the Wraith Chain, and erratic drift that defies prediction. Which path will your Reaper take?

Field guide

Know the river.

Gather souls. Reach the docks. Bank more tribute than your rivals.

Trial waters: nine Wells and four southern Stone Docks Schematic, not to scale. Five cross-shaped Wells in the upper rank, four in the lower rank, and four Stone Docks at the bottom. SOUTHERN SHORE / FOUR STONE DOCKS
  1. 01

    Collect souls

    Nine cross-shaped Wells start full of souls. Move onto a soul to collect it automatically. Your vessel carries up to three.

  2. 02

    Manage the Wells

    Nearby souls help empty tiles replenish. Stripping an entire Well shuts it down for the rest of the match. Leave souls behind to keep harvesting later.

  3. 03

    Deliver to docks

    Reach any Stone Dock on the southern shore to unload automatically. Each soul banks one tribute. Deliver early or wait for a full hold.

  4. 04

    Disrupt rivals

    Hit a rival with a Wraith Chain to banish them temporarily. They return with cargo intact, buying you time and position.

Individual match placement · after 500 turns

Tribute first. Then the tie-breakers.

  1. 1Most banked tribute
  2. 2Tie-breaker: Most carried souls
  3. 3Tie-breaker: Fewest banishments suffered

Tied bots share match rank. Match placements update TrueSkill ratings to order the live leaderboard.

For the full rules, setup and detailed guidance, explore the Starter Kit.

Baseline strategies

Four Reapers Waiting To Hunt.

Four baseline strategies to learn from. Your Reaper can take another path.

I / Collection

Midas

The Hoarder

Chases the nearest soul and docks when full or empty. Takes everything immediately, leaving conservation to others.

Greedy collection

II / Preservation

Charon

The Guide

Harvests from dense clusters and returns when full. Protects Wells so they continue replenishing.

Sustainable gathering

III / Denial

Cerberus

The Warden

Fires at rivals ahead, then wanders. Focuses on disruption rather than banking souls.

Aggressive denial

IV / Uncertainty

The Lethean Shade

The wandering vessel

Moves, turns, or waits at random. Follows no planned route and fires no attacks.

Unpredictable movement

Matches can pair your bots with other entrants and these baselines.

Competition rules

Send your hunters. Earn your place.

01 / Build & submit

Three bot slots.

Enter up to three named bots and refine them over time. Review match replays to improve your strategy before uploading updates.

02 / Compete

Find your place on the ladder.

Every match updates your bot rating on the live leaderboard. Test frequently, learn from match results, and climb.

03 / Final judgment

Make your claim stick.

The live ladder is provisional. Top qualifying bots advance to the championship rounds and Grand Final to determine the winners.

Your next move

Build your Reaper.

Start with the engine. Test a strategy. Bring it to the river.

  1. Start with the Starter Kit for setup and the full rules.
  2. Learn the actions and test against the baseline bots.
  3. Check the portal’s submission rules and deadline.
  4. Register your bots and refine your strategy using replays.

Submissions closed