I really like this one. Can you go more in details on how you made this? Is this your own engine? How did you make the maps? Do you have a map editor? Did you draw the art of the characters?
Thanks :) It's my own engine, but makes use of libGDX to help with some low-level rendering since plain OpenGL is a bit too raw for my taste. It's hacked open so I can use my own game loops and own everything else.
Maps are mostly randomly generated, so they're almost entirely just code. The small chunks which are static I define inline as a 2d array of chars, like the roguelikes of yore.
I do a loads of my own artwork, but for the most part it's modifying, re-coloring and extending existing tilesets. It's much easier to follow a consistent design language than invent your own. This game is mostly based brilliant work from https://pita.itch.io/, and http://www.squidi.net/pixel/char.default.php
My entire workspace is 68,400 lines, not lines of code but raw line count of all *.java files - so it's a bit susceptible to the formatting style. This represents ~5 years of active development, a couple of significant refactors, and 9 games worth of left-over bits and pieces. I haven't worked on this engine for a few years now, except for the 7DRL game jams because it's more complete and capable than my current project.