Not sure that I would call it a "game", but my first prototype/test in Ren'Py is called "Vorfal". It's German for "Incident", not because I am German but honestly just because it sounded cool. (Although wife actually is of German decent).
About a month ago I started looking into Visual Novel development after learning about Ren'Py via some random video. I have been writing a story (just for fun) for around 8 months, when I realized that I wasn't satisfied with the limitations of the normal "book format" as compared to what I wanted to express... After learning about Ren'Py, it rekinkled my desire to continue working on my story, but with the goal of converting it to a Visual Novel.
Anyway, so yeah I decided to challenge myself to create a prototype game in order to learn a lot of the basic mechanics in Ren'Py. When I started, I decided to use some actual real photographs I had taken while on a trip years ago. I ran them through a compression tool to give them an "old console compressed look". Sadly, I ended up only having 3 actual decent images that made sense when used in a VN format... But since it was more of a test/demo, I said "ah well I'll see what I can come up with".
The end result was the Vorfall Prototype... Which is a very short and silly "game" where you take wake up in an unknown place, have to solve one puzzle, take a dump, and then escape by jumping out the window... Lol...
As silly as it sounds... I had a lot of fun learning through trial and error. There's something special about seeing something work correctly, after you've been fiddling with it for an hour... Lol. I literally could not stop smiling when I figured out how to properly add a sound effect for navigating between the rooms.
Anyway, by no means would I claim my prototype is a "full game", I guess it still counts as part of the learning progress. :p