MM25d_Intall_Notes.txt
This worked on my steam deck as well as a linux desktop (PopOS! - ubuntu based)

1) Download MM2.5d - http://petersjostrand.com/
2) Install Bottles, Flatseal, and BoilR from discover store
3) OPTIONAL - Run flatseal and allow bottles access to filesystem if using SD card or alternate directory
4) Create a Bottle
    a) Go to bottles preferences and install caffe runner
        - Hamburger menu -> preferences
        - Runners tab -> caffe
        - install soda-7.0-8 and caffe-7.20
    b) Create new Bottle
        - name it and choose "gaming" preset
    c) Go to the named bottle you created -> details, click settings
        - under runner choose soda-7.0-8 (caffe-7.20 will be used later)
5) Add dependencies to Bottle
    a) Go to the named bottle details, click dependencies
       - install dotnet48
       - install mono
       - instsall xna40
       -> it is ok if these have some errors as long as they complete
6) Install mega man 2.5d (using soda-7.0-8 runner)
    a) Go to the named bottle and click "Run Executable"
    b) Choose the MM25d installer downloaded above
    c) click through installer as prompted
        - if installer fails to launch, try the other runner (soda/caffe)
7) Add shortcut to Bottle and add to bottle library
    a) should automatically add mm25dgame if installer completes 
        - if MM25DGame does not show under "Programs", the manually select through "Add Shortcuts"
    b) add to this to library in bottles through the hamburger icon next to the play icon (needed for BoilR)
8) Change bottle to caffe-7.20 runner in bottle settings
    a) click the play button to test the game!
    -> for some reason for me I had to install with soda as the runner, but play with caffe as the runner
9) Run BoilR to add to Steam
    a) launch BoilR
    b) select the MMM25DGame added to bottles library
        - deselect other items 
    c) click the import icon in the lower left to add to steam
10) Launch from Steam Deck in desktop or gaming mode from steam library
    a) OPTIONAL - Rename shortcut as desired and add artwork (steamgriddb/sdgboop works)
    b) OPTIONAL - Set controls through Steam if desired (default controls are keyboard)
        -> "MM 2.5d Deck" is what I tried to export to community with "Mega Man 2.5D" as shortcut name
    c) OPTIONAL - Set the steam deck shortcut to 1280x720 resolution on launch