Thank you very much! Glad you liked it!
I've used the amazing lvllvl text art editor for creating the scenes (after merging in a pixel art editor the tiles I had designed with a selection of mrmo and others). I've also created in lvllvl a 7 colors palette to match bipsi's limitations. I'm guessing you're impressed with the images that look pretty complex: there's an option in lvllvl to convert a regular image to a selection of tiles. I've then tweaked the outcome.
Finally, I've adapted a bipsi plugin to import my levels.