steps to create an AppImage

often run into this issue with documentation where the documentation is trying to be as exhaustive as possible and as such make the simplest use case impossible to unearth.

https://docs.appimage.org/packaging-guide/manual.html#creating-an-appdir-manually

this documentation seems ok enough but I'm pretty sure I don't need 99% of what they claim.

I'm in the use case where I built something from unity. I have a folder that contains my main binary and then ton and tons and tons of other junk.

when you click on the binary it runs perfectly it has an icon and all.

How do I just put that entire folder into an .appimage file including instructions on what's the right binary to run?

seems like all I need to do is create a folder named MyUnityGame.AppDir and inside have my whole folder I mentioned plus a .desktop file that points to the binary and that's it right?

all the rest sounds like it would apply to something that's not self contained / that has dependencies, which isn't my case.

what's next once I have my .desktop?

(and most error-proof) to use a precompiled one from this repository.

where's the precompiled AppRun file?

EDIT : I guess it's this one : https://github.com/AppImage/AppImageKit/blob/master/resources/AppRun

can I just have it as :

#!/bin/sh
exec myunitygame.desktop "$@"

seems like the rest is superfluous in my case

I don't understand what exactly you are looking for. Here is bash script which I have created to make Appimage for Brave browser. This assumes you have already downloaded brave browser deb file. You also need to download appimagetool.

#!/bin/bash -x

set +e
APP=Brave
patharch=x86_64
package="brave-browser_1.33.100_amd64.deb"
URL="https://github.com/brave/brave-browser/releases/"
if  [ ! -f $package ]; then
    wget -c $URL$package
else
    echo "$package file exists"
fi

mkdir -p ./$APP.AppDir
rm -rf ./$APP.AppDir/*
cd $APP.AppDir/
find ../ -name *.deb -exec dpkg -x \{\} . \;

cp opt/brave.com/brave/product_logo_48.png ./Brave.png
# find . -name $APP.desktop -exec cp \{\} . \;
# find -name $APP.png -exec cp \{\} . \;

cat > $APP.desktop <<EOF
[Desktop Entry]
Type=Application
Name=brave-browser
Exec=brave-browser %U
StartupNotify=true
Icon=Brave
Categories=Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml_xml;image/webp;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;
EOF

mkdir -p usr/bin/
mv ./opt/brave.com/brave/* usr/bin/ ; rm -rf ./opt

AppRun="AppRun"

if  [ ! -f ../../$AppRun ]; then
    wget -c https://github.com/AppImage/AppImageKit/releases/download/continuous/AppRun-${patharch} -O AppRun
else
    cp ../../AppRun .
fi
chmod a+x AppRun

# generate_type2_appimage
cd ..
VERSION=""
VERSION=$VERSION ../appimagetool -v -n ./$APP.AppDir/

if [ -d "./$APP.AppDir/" ] ; then
  rm -rf ./$APP.AppDir
fi

Hope this helps.