Skip to content


Repository files navigation


This is a clone of the MarioAI engine Additionally all dependencies are managed via Maven.
gym_marioai is a python gym interface that communicates with a java wrapper around the original MarioAI engine.


This instruction will help you to get the environment up and running.
It is necessary to start the java server first, and then initiate the connection on the python side.
A precompiled version of the server .jar is included in the gym_marioai package. You will require Java 1.8 to execute it.

Youtube video:

Watch a video of how Mario learns behavior using this library:

1) Requirements

  • Java runtime 1.8 (java -version should output something like ... version "1.8.*").
  • python 3.7, pip

2) install the package

in ./gym_marioai, run pip install .

3) run the server

in ./gym_marioai/gym-marioai/server/, run java -jar ./marioai-server-0.1-jar-with-dependencies.jar. The parameter -p allows to specify a port (default is 8080)

4) run the demo

navigate to ./gym_marioai/demo/, then run python This will open a separate window with Mario performing random actions in the environment.

MacOS additional steps

to be able to control Mario when running on MacOS, additional permissions must be granted. This can be done via System Preferences -> Security & Privacy -> Tab 'Privacy'. In the categories 'Accessibility' and 'Input-Monitoring', open the lock to allow editing and add your respective IDE (e.g. Visual Studio Code or Terminal) to the list. Then, run the program with administrator permissions: sudo python


Initialization of the environment:
The environment is entirely configured using the gym.make() function. Here is an overview of all available parameters including its default values:

env = gym.make("Marioai-v0", host, port, render, rf_width, rf_height, 
               difficulty, seed, level_path, level_length, max_steps, 
               reward_settings, compact_observation, trace_length,
               repeat_action_until_new_observation, enabled_actions)

This will attempt to connect to a running server instance on host:port.

parameter default value description
host 'localhost' server address
port 8080 server port
render False
rf_width 11 receptive field width
rf_height 7 receptive field height
difficulty 0
seed 1000
level_path "None" takes precedence over seed if other than "None"
level_length 80
max_steps 0
reward_settings RewardSettings() option to change the default reward function, see below
compact_observation False will use only a hash value if set to True. see below for more information
trace_length 1 use consecutive frames as state information. You can also use a FrameStack wrapper (
repeat_action_until_new_observation 2

Modifying the reward function

from gym_marioai import RewardSettings

reward_settings = RewardSettings(progress=1, timestep=-.1, mario_mode=10, kill=1, 
                                 coin=1, win=100, dead=-100, cliff=25)

Use custom levels

from gym_marioai import levels
env = gym.make("Marioai-v0", host='localhost', port=8080,

It is also possible to create new levels using the level generator that is included in the MarioAI engine. If a level is stored as example.lvl, you can use it by passing the absolute path as a string.


if compact_observation is set to true, the environment will return hash values of range int32. This is particularly useful for Tabular Reinforcement Learning. Otherwise, the receptive field is represented as numpy array of dtype int8 and shape rf_width * rf_height * 4. It contains for every cell, for every feature of [enemy, obstacle, coin, itembox], a 1 if included in the cell and a 0 otherwise.

the reset() function

env.reset(seed=None, difficulty=None, level_path="None", render=None)
Provides the possibility to change the level parameters on a reset. This is useful e.g. if you want the agent to train on random levels.


1) Requirements

  • JDK 1.8 with Maven plugin

2) Build and install MarioAI engine

  • cd marioai-engine
  • mvn clean package install
  • (optionally build JAR with sources): mvn source:jar install

3) Build and run the server

  • cd marioai-server
  • mvn clean package
  • java -jar target/marioai-server-0.1-jar-with-dependencies.jar

4) Modifying the protobuf interface

  • interface specified in marioai-server/src/main/resources/proto/mario.proto
  • the python proto needs to be recompiled manually, e.g. using the makepythonproto bash script

(to publish modifications on marioai-server, you will probably want to update the precompiled .jar in the python package as well.)