So I just wanted to add KeeperRL to libregamewiki. Their advertisement makes it looks like the gratis version (ASCII version without the commercial assets) is free -- they state it on their website and the whole repo that can be compiled and played is licensed GPLv2. However, that is not true because, as I have found, there is this sneaky little line hidden in COPYING-MEDIA:
Every file located in directory 'data_free' is granted under the Creative Commons BY-NC-SA licence.
So the game is non-free, but it's just because of a few GUI elements and configs that could easily be replaced (or maybe even just deleted). Only a relatively small effort would be required to make the game free.
I am creating this thread firstly in order to highlight this fact so that there is a bigger chance someone will liberate the game, and secondly to ask you whether you know about other similar low hanging fruit projects like this. I'll start a list of these games, which I will keep updating.
the list: