Environment Variables link

Ren'Py accepts a number of environment variables that influence its behavior. These environment variables may disappear or change between Ren'Py releases.

The following environment variables control the behavior of Ren'Py:

RENPY_DISABLE_JOYSTICK
If set, joystick detection is disabled. Use this if a faulty joystick is causing Ren'Py to advance when not desired.
RENPY_DISABLE_FULLSCREEN
If set, Ren'Py will refuse to go into fullscreen mode.
RENPY_DISABLE_SOUND
This prevents sound playback from occurring. If this variable contains "pss", sound playback will be disabled.
RENPY_DRAWABLE_RESOLUTION_TEXT
If set to 0, Ren'Py will not use draw text at the screen's resolution.
RENPY_EDIT_PY
The path to an .edit.py file telling Ren'Py how to invoke a text editor. See Text Editor Integration for more information.
RENPY_GL_ENVIRON
Sets the OpenGL texture environment.
RENPY_GL_RTT
Sets the OpenGL render-to-texture method.
RENPY_GL_VSYNC
This determines if Ren'Py will attempt to synchronize with the display's vertical refresh. (This prevents tearing, at the cost of potentially lowering framerate.) Set this to "0" to disable synchronization, or "1" to sync to every vertical refresh.
RENPY_LANGUAGE
If set, gives the translation language Ren'Py will use.
RENPY_LESS_MEMORY
This causes Ren'Py to reduce its memory usage, in exchange for reductions in speed.
RENPY_LESS_MOUSE
This causes Ren'Py to disable the mouse at all times.
RENPY_LESS_PAUSES
This causes Ren'Py to disable the pauses created by the {p} and {w} text tags.
RENPY_LESS_UPDATES
This causes Ren'Py to reduce the number of screen updates that occur.
RENPY_SCREENSHOT_PATTERN
A pattern used to create screenshot filenames. It should contain a single %d substitution in it. For example, setting this to "screenshot%04d.jpg" will cause Ren'Py to write out jpeg screenshots rather than the usual pngs.
RENPY_SIMPLE_EXCEPTIONS
When set, this disables Ren'Py's graphical exception handling.
RENPY_SKIP_MAIN_MENU
When set, skips the main menu.
RENPY_SKIP_SPLASHSCREEN
When set, skips the splashscreen.
RENPY_SOUND_BUFSIZE
This controls the sound buffer size. Values larger than the default (2048) can prevent sound from skipping, at the cost of a larger delay from when a sound is invoked to when it is played.
RENPY_TIMEWARP
This can be set to make time run faster or slower. For example, setting a timewarp of 0.5 makes things run at half-speed, while a timewarp of 2.0 makes everything run at twice normal speed.
RENPY_USE_DRAWABLE_RESOLUTION
If set to 0, Ren'Py will perform certain operations (including dissolve transforms and text rendering) at the game's virtual resolution rather than the screen's native resolution.
RENPY_VARIANT
This should be set to a space-separated list of screen variants that Ren'Py is expected to use.

As Ren'Py uses SDL, its behavior can also be controlled by the SDL environment variables.

At startup, Ren'Py will look in the Ren'Py directory (the one containing renpy.exe or renpy.py) for the file "environment.txt". If it exists, it will be evaluated as a python file, and the values defined in that file will be used as the default values of environment variables.