Hi, easiest (“Unix”) way is to change into the game’s directory with the terminal and execute easyrpg-player (assuming it is added to the PATH environment variable.
A more Desktop-like approach:
Let’s say you have a folder consisting of extracted RPG Maker 2000/2003 games in /home/someuser/Games/RPG.
Create a Desktop shortcut and use the following command: easyrpg-player --project-path "/home/someuser/Games/RPG" --window
When you click on that shortcut, our game browser will launch and you can select a game.
You can find other command line options here: https://easyrpg.org/player/manual/#_options (some options only make sense when you launch a game directly and not the game browser, though).