MSFS2020.ARPC is an open-source patch that fixes the sky colors in Microsoft Flight Simulator 2020 (MSFS2020) by replacing atmospheric coefficients, resulting in a more realistic sky rendering.

This tool patches the atmospheric coefficients in-memory, without modifying any game files. As a result, it prevents the patch from being overwritten with updates and offers a simpler installation and removal process.

This tool owes its existence to the discovery made by Biology2394/FarukEroglu2048. See credits.

1. Download the latest release of MSFS2020.ARPC.zip.
2. Drag and drop the dinput8.dll, MSFS2020.ARPC.asi and (optional) MSFS2020.ARPC.ini files from the archive into your MSFS installation directory.

The installation path containing FlightSimulator.exe may vary depending on where you obtained and installed MSFS:

• C:\XboxGames\Microsoft Flight Simulator\Content

  [!NOTE] This folder might not exist if you have an older install, convert to the modern install.
  (See https://parallel42.com/blogs/wiki/converting-my-sim-install-from-legacy-to-modern)

• C:\Program Files\WindowsApps\Microsoft.FlightSimulator_1.34.16.0_x64__8wekyb3d8bbwe

  [!IMPORTANT] To access this folder you need to take ownership of the WindowsApps folder.
  (See https://forums.flightsimulator.com/t/take-ownership-of-the-windows-apps-folders/388969)

• C:\Program Files (x86)\Steam\steamapps\common\MicrosoftFlightSimulator

MSFS2020.ARPC.ini allows you to customize the patch.

; WARNING: Do not leave out the values; remove the entire line instead.
;          Entering invalid values may cause the game to crash.

[COEFFICIENTS]
RED = 0.002723
GREEN = 0.001831
BLUE = -0.000083096

; Enable the live editing functionality
; When enabled, changes to the coefficients reflect in-game when saved
LIVE_EDITING_ENABLED = false ; Set to 'true' to enable live editing


[TOGGLE]
; Enable the toggle functionality
ENABLED = false ; Set to 'true' to enable the toggle feature

; Key code for toggling (See https://learn.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes)
KEY_CODE = 0x2D ; INSERT

; Enable or disable key modifiers
HOLD_ALT = false ; Set to 'true' to use Alt as a modifier
HOLD_CTRL = true ; Set to 'false' to disable Ctrl as a modifier
HOLD_SHIFT = false ; Set to 'true' to use Shift as a modifier

• Build Tools for Visual Studio 2022
• xmake

Run in terminal:

xmake

GitHub Repository: https://github.com/FarukEroglu2048/ARPC

MSFS Forum: https://forums.flightsimulator.com/t/replace-the-atmosphere-parameters-with-more-accurate-ones-from-arpc/607603/1

.asi loader by ThirteenAG

GitHub Repository: https://github.com/ThirteenAG/Ultimate-ASI-Loader