Ruby MMO: massively multiplayer online programming challenge
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Ruby MMO

Ruby MMO is a programming challenge in which players compete to gain the highest level in an MMO simulation.

How to play

Fork this repo and commit a module inside the /players directory. The module is then used to extend a player object with a couple of methods:

  1. The move method returns an array with two elements: the method to be called (can be one of :attack or :rest), and the method arguments. In the case of :attack the argument should be an instance of an opponent Player (see below for how to get this). In the case of :rest no argument is required. See the examples in the /players directory.

  2. to_s (optional) returns the name of the player.

Order of Play

The player order is shuffled each round. If multiple players attack the same opponent, the attacks are grouped so that the largest group attacks first and then remaining attackers are random (thanks to @iyonius).

Levelling Up

For each conquered opponent, the attacker gains the amount of experience equal to the opponent's max health. Group attackers split the experience equally. If a player's experience crosses the threshold for levelling up, that player's max health, strength, and defence will all be increased (according to the schedule in engine/player.rb).


The player modules have access to the hash. This hash contains all the players and monsters in the world and their current stats. For example, to get the stats of a random player you could do:

player_count =[:players].count
opponent =[:players].select{|p|p != self}[rand(player_count - 1)]

The select is to ensure the player is not fighting itself.

There is also a method alive that returns false if the player is dead.


  1. No cheating by overriding classes, methods, or instance variables.
  2. Cheating players will be moved to the cheaters/ directory.

@DanKnox came up with a dominating technique that involves dynamically creating multiple player modules. In order to mitigate the strength of this technique, a third rule seems necessary:

  1. No more than 3 player instances per Github account.

Running the simulation

./engine.rb -r 100 where -r sets the number of rounds (default is 10).


The player with the highest level and experience wins.


Sprint (./multi_run.rb -r 1000 -o 10)

Jbttn won 388 times
Valentin won 251 times
*noob* won 100 times
strax won 73 times
Angry Mamay won 64 times
Izidor won 37 times
Lachesis won 26 times
Clotho won 18 times
Atropos won 18 times
Jax won 16 times
__pwned_clone_left won 4 times
Van Diagram won 3 times
Z Cloud Strife won 1 times
limekin won 1 times

Race (./multi_run.rb -r 1000 -o 100)

Chuck Norris won 181 times
__pwned won 90 times
flipback won 82 times
Eric the Kill Steal won 76 times
Atropos won 66 times
__pwned_clone_right won 65 times
Z Cloud Strife won 61 times
Jax won 47 times
Clotho won 47 times
__pwned_clone_left won 42 times
Emmanuel, the new guy won 42 times
Lachesis won 39 times
Van Diagram won 37 times
Izidor won 37 times
strax won 13 times
| Drowsy Leo | won 12 times
Rogue Leader won 12 times
limekin won 11 times
Michael won 7 times
*noob* won 5 times
rots won 5 times
*No rest for the wicked* won 4 times
Angry Mamay won 4 times
Ian Terrell won 3 times
Cossack Mamay won 3 times
Jayaram won 2 times
Teeler won 2 times
Jack won 2 times
South Pole Steve won 1 times
A Tabby Cat won 1 times
Sir Samsonite won 1 times

Endurance (./multi_run.rb -r 1000 -o 1000)

Chuck Norris won 158 times
Eric the Kill Steal won 123 times
Z Cloud Strife won 118 times
Lachesis won 69 times
Atropos won 66 times
flipback won 66 times
__pwned won 53 times
__pwned_clone_right won 47 times
Clotho won 39 times
Emmanuel, the new guy won 39 times
__pwned_clone_left won 32 times
Van Diagram won 32 times
Izidor won 29 times
Jax won 22 times
Michael won 18 times
| Drowsy Leo | won 15 times
limekin won 15 times
Ian Terrell won 10 times
Rogue Leader won 10 times
*No rest for the wicked* won 8 times
Angry Mamay won 5 times
strax won 4 times
rots won 4 times
*noob* won 4 times
Sir Samsonite won 3 times
Teeler won 3 times
Jack won 2 times
Dan Knox won 1 times
Crazy Carl won 1 times
Jayaram won 1 times
Cossack Mamay won 1 times
South Pole Steve won 1 times
A Tabby Cat won 1 times