Model and animation was done in blender: https://www.blender.org/
Background is AI generated using this: https://nmkd.itch.io/t2i-gui
All of the editing, including the title text, menu options and the pencil filters were done in PhotoFiltre Studio X: https://www.photofiltre-studio.com/news-en.htm
This is a very weak program compared to photoshop or even gimp so if you use any of those daily, there is no need to use this I think. But I have been using it for almost two decades and it is really great for simple editing like this because of how easy it is to work with. I use gimp for more complex things.
As for the gif itself:
I recorded the game with OBS Studio (I didn't update it for years so I don't really know if it still works the same): https://obsproject.com/
I then uploaded it to: https://ezgif.com/video-to-gif
There I cut it to size, clip the length and converted it to gif.