Install the Elden Ring Coop mod by saving this script (download zip) and execute it

elden_ring_coop_install.bat

@echo off
setlocal

for /f "usebackq tokens=1,2,*" %%B IN (`reg query "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" /v Desktop`) do set DESKTOP=%%D
for /f %%i in ('echo %DESKTOP%') do set DESKTOP=%%i

if NOT EXIST "%DESKTOP%/" (
	echo error: Desktop not found
	goto :END
)

echo Desktop found at %DESKTOP%

cd "%APPDATA%"

set "version=1.5.1"
set "archive=%APPDATA%\eldenringcoop_v%version%.zip"

IF NOT EXIST "%archive%" (
	echo [1/5] Downloading the mod from Github ^(%version%^)
	call:Download "https://github.com/LukeYui/EldenRingSeamlessCoopRelease/releases/download/v.%version%/betarealeasecoop%version%.zip" "%archive%"
) ELSE (
	echo [1/5] %archive% already downloaded
)

if NOT EXIST "%archive%" (
	echo error: Download failed
	goto :END
)


set "tempdir=%APPDATA%\eldenringcoop_v%version%"
if NOT EXIST "%tempdir%\" (
	echo [2/5] Unziping archive
	powershell Expand-Archive "%archive%" -DestinationPath "%tempdir%"
)

if NOT EXIST "%tempdir%\" (
	echo error: Unziping failed
	goto :END
)

set "eldenringdir=C:\Program Files (x86)\Steam\steamapps\common\ELDEN RING\Game"
if NOT EXIST "%eldenringdir%\" (
	set "eldenringdir=C:\Program Files\Steam\steamapps\common\ELDEN RING\Game"
)

if NOT EXIST "%eldenringdir%\" (
	ECHO error: Elden Ring's Steam folder not found
	goto :END
)

if NOT EXIST "%eldenringdir%\launch_elden_ring_seamlesscoop.exe" (
	echo [3/5] Moving files to Steam folder
	xcopy /S "%tempdir%" "%eldenringdir%"
) ELSE (
	echo [3/5] Updating mod ^(removing old files^)
	xcopy /Y "%eldenringdir%\SeamlessCoop\seamlesscoopsettings.ini" "%tempdir%\SeamlessCoop\seamlesscoopsettings.ini"
	rmdir /S /Q "%eldenringdir%\SeamlessCoop"
	xcopy /Y /S "%tempdir%" "%eldenringdir%"
)


if NOT EXIST "%eldenringdir%\launch_elden_ring_seamlesscoop.exe" (
	echo error: Moving failed
	goto :END
)

set "shortcut=%DESKTOP%\Elden Ring Coop.lnk"
if NOT EXIST "%shortcut%" (
	echo [4/5] Creating Desktop shortcuts
	call:CreateShortcut "%eldenringdir%\launch_elden_ring_seamlesscoop.exe" "%shortcut%"
	call:CreateShortcut "%eldenringdir%\SeamlessCoop\seamlesscoopsettings.ini" "%DESKTOP%\Elden Ring Coop Password.lnk"
) ELSE (
	echo [4/5] Shortcuts created
)

if NOT EXIST "%shortcut%" (
	echo error: Shortcuts creation failed
)

echo Please set a coop password after 'cooppassword = '
notepad.exe "%eldenringdir%\SeamlessCoop\seamlesscoopsettings.ini"

goto :END

:CreateShortcut
	@echo off
	(
		echo $SourceFilePath = %1
		echo $ShortcutPath = %2
		echo $WScriptObj = New-Object -ComObject ^("WScript.Shell"^)
		echo $shortcut = $WscriptObj.CreateShortcut^($ShortcutPath^)
		echo $shortcut.TargetPath = $SourceFilePath
		echo $Shortcut.WorkingDirectory = "%eldenringdir%"
		echo $shortcut.Save^(^)
	) > shortcut.ps1
	powershell -executionpolicy remotesigned -File shortcut.ps1
	del shortcut.ps1
	goto :EOF

:Download
	set "URL=%1"
	set "SaveAs=%2"
	powershell "Import-Module BitsTransfer; Start-BitsTransfer '%URL%' '%SaveAs%'"
	goto :EOF

:END
	echo [5/5] Removing temporary files
	:: if EXIST "%tempdir%" rmdir /S /Q "%tempdir%"
	echo End of the script
	pause
	goto :EOF

ersc_install_steamdeck.sh

#!/bin/bash

error()
{
    echo -e "error: $@" > /dev/stderr
    msg --error "$@"
    exit 1
}

msg()
{
	kdialog "$@" 2>/dev/null
	if [[ $? -ne 0 ]]; then
		error "Aborted during $@"
	fi
}

DESKTOP="$HOME/Desktop"

if [[ ! -d "$DESKTOP" ]]; then
	error "Desktop not found"
fi

cd /tmp

url="https://github.com/LukeYui/EldenRingSeamlessCoopRelease/releases/latest/download/ersc.zip"

true_url="$(curl -L -i -s $url  | awk '/^location:/ {print $2}' | head -n 1)"

version="$(echo $true_url | cut -d '/' -f 8)"
archive="/tmp/ersc_${version}.zip"

if [[ ! -f $archive ]]; then
	msg --passivepopup "Telechargement de Elden Ring Seamless Coop (ERSC ${version})"
	echo "[1/5] Downloading the mod from Github (${version})"
	wget -q -O "${archive}" "${url}"
else
	echo "[1/5] "${archive}" already downloaded"
fi

if [[ ! -f "${archive}" ]]; then
	error "Download failed"
fi


tempdir="/tmp/ersc_${version}"
if [[ ! -d "${tempdir}" ]]; then
	msg --passivepopup "Extraction des fichiers (ERSC ${version})"
	echo "[2/5] Unziping archive"
	# mkdir -p "${tempdir}"
	unzip "${archive}" -d "${tempdir}"
fi

if [[ ! -d "${tempdir}" ]]; then
	error "Unziping failed"
fi

eldenringdir="$HOME/.steam/steam/steamapps/common/ELDEN RING/Game"

if [[ ! -d "${eldenringdir}" ]]; then
	error "Elden Ring's Steam folder not found"
fi

launcher="${eldenringdir}/ersc_launcher.exe"
if [[ ! -f "${launcher}" ]]; then
	echo "[3/5] Moving files to Steam folder"
	cp -r "${tempdir}/." "${eldenringdir}"
else
	echo "[3/5] Updating mod (removing old files)"
	# diff -q "${eldenringdir}/SeamlessCoop/ersc_settings.ini" "${tempdir}/SeamlessCoop/ersc_settings.ini" && {
	#	kompare "${eldenringdir}/SeamlessCoop/ersc_settings.ini" "${tempdir}/SeamlessCoop/ersc_settings.ini"
	#}
	cp "${eldenringdir}/SeamlessCoop/ersc_settings.ini" "${tempdir}/SeamlessCoop"
	cp -r "${tempdir}" "${eldenringdir}"
fi

if [[ ! -f "${launcher}" ]]; then
	error "Moving failed"
fi

chmod 755 "${launcher}"

create_shortcut()
{
cat > "$1" << EOF
#!/usr/bin/env xdg-open
	[Desktop Entry]
	Name=$2
	Exec=$3
	Icon=${4:-/home/deck/.local/share/icons/emudeck/EmuDeck.png}
	Terminal=false
	Type=Application
	Categories=Game;
	StartupNotify=false
EOF
chmod 755 "$1"
}

shortcut="${DESKTOP}/Elden Ring Coop Password.desktop"
if [[ ! -f "${shortcut}" ]]; then
	msg --passivepopup "Creation du raccourci du fichier de config sur le bureau"
	echo "[4/5] Creating Desktop shortcuts"
	# create_shortcut "${shortcut}" "Elden Ring Coop" "${launcher}" "${HOME}/.steam/steam/steam/games/2e048bfc2073ca30804ed5b8c454a9ca0e2f98de.ico"
	create_shortcut "${shortcut}" "Elden Ring Coop Password" "xdg-open '${eldenringdir}/SeamlessCoop/ersc_settings.ini'" "accessories-text-editor"
else
	echo "[4/5] Shortcuts created"
fi

if [[ ! -f "${shortcut}" ]]; then
	error "Shortcuts creation failed"
fi

echo "Please set a coop password after 'cooppassword = '"
msg --msgbox "Definir un mot de passe de session 'cooppassword = ' \nRappel clavier     (STEAM)+X"
xdg-open "${eldenringdir}/SeamlessCoop/ersc_settings.ini" 2>/dev/null
msg --yesno "Mot de passe defini ? ERSC ne demarrera pas sans."

echo "Please right click on ${launcher} and add it to steam"
msg --msgbox "Faites un clic droit / L2 sur ${launcher} et selectionnez 'Add to steam'"
xdg-open "${eldenringdir}" 2>/dev/null
msg --yesno "Clic droit / L2 sur ${launcher} et selectionner 'Add to steam' réussi ?"

echo "Please launch ersc_launcher.exe with compatibility mode Pronton"
msg --msgbox "Changer l'option steam pour ersc_launcher.exe en mode de compatibilité Proton 9.0-4 (clic droit / L2 -> propriétés)"
steam
msg --yesno "Compatibilité 9.0-4 pour ersc_launcher.exe réussi ? ((clic droit / L2 -> propriétés, cocher la case, valider Proton 9.O-4 )"

# echo "[5/5] Removing temporary files"
# rm -r "${tempdir}"