Cheers,
From what I read, your script already exists as a snippet. It’s called Ditto, which does the magic you need. Do you have any experience with HTML/CSS? In that case, using Ditto is like a walk in the park. Ditto is pre-installed in MODx, but a new version has been released (2.0.2), so I recommend that you download this one before doing anything else.
Call Ditto from the website you’d like to work as a list of games, using [[Ditto]] with your choice of attributes. To show a thumbnail of the game, create a picture Template Variable, hook it up to your game template, and then add it to the Ditto template.
If you’re new with MODx, I recommend reading through the MODx documentation first, as my description might seem a bit Greek until you understand how the system works