Requirements:
A legitimate copy of Pokémon Black/White (2010) [first version]
An account on the PokeMMO website
Java version 17 on your Steam Deck System
Steps:
Download PokeMMO:
Visit the PokeMMO website and download the file from this link.
Install Java v.17:
Follow the guide available on GitHub.
Or open the terminal on your Steam Deck and enter the following commands:
git clone https://github.com/BlackCorsair/install-jdk-on-steam-deck.git && \
JDK_VERSION=17 ./install-jdk-on-steam-deck/scripts/install-jdk.sh
Note: On my system, I have used JDK version 21 and it works fine, but PokeMMO requires JDK-17 in the .sh file. Therefore, this guide follows that directive.
Prepare the PokeMMO File:
Unzip the file downloaded from PokeMMO.
Open the PokeMMO.sh file with a text editor.
Modify the line:
java -Xmx384M $os_flags -Dfile.encoding="UTF-8" -cp PokeMMO.exe com.pokeemu.client.Clientto:
/home/deck/.local/jdk/jdk-17.0.8/bin/java -Xmx384M $os_flags -Dfile.encoding="UTF-8" -cp PokeMMO.exe com.pokeemu.client.Client
Run PokeMMO:
Save the changes and close the editor.
From the terminal, run the PokeMMO.sh file to ensure everything is working correctly:
./PokeMMO.sh
Associate the ROMs:
Follow the instructions on the launch screen to associate the required ROMs.
Pokémon Black/White (2010) is mandatory, while other ROMs are optional and can be added later to enhance gameplay.
Register an Account:
Before starting to play, register on the PokeMMO website using this link.
Adding PokeMMO to Your Steam Library:
Once you have completed all the steps, you can add PokeMMO.sh to your Steam library.
Open Steam in desktop mode.
Click on "Add a Non-Steam Game" at the bottom left.
Select PokeMMO.sh from the list of files and click "Add Selected Programs."
Customize the game's appearance in your library by adding the necessary images (cover art, icons, etc.) to make it look appealing by https://www.steamgriddb.com/game/5249074.