I remember something like this one, for a different "game" called FPS creator:
Wuzzy wrote:6. Minetest sometimes locks cursor to center of screen even if window is not active (
issue 3507)
Sometimes when trying to load a level (you create levels and then load/test them), the game would crash for seemingly no reason (only happens occasionally), then the cursor would be stuck in the middle of the screen, and the only way to get it un-stuck is to either restart the machine or go to the task manager (yes, windoze; no I don't still use it), navigate to the process and end it, using only the keyboard navigation.
They never fixed it, even though it is 6 years later (I could not find anything related to the issue anywhere else, so it isn't likely that they even know about it). It may be fixed in some new version (all of the old bug reports got moved to a "classic" section, which usually means there's a new overhauled version and they call the older system "classic"), but if it is fixed, I doubt that is because they deliberately tried to fix it, but rather it would have been fixed "by accident".
Notice how the topic name doesn't really have anything to do with the problem; this hinders its visibility to the developers. A topic named "[Bug] Level doesn't load, Cursor gets stuck, can't do anything!" would probably get much more attention than one just named "game testing problem". If you find a problem that is as devastating as this one, don't just name it something like "cant play game pls help!!!1!one", rather name it something like "[Bug] Black screen, Cannot load anything" or whatever is equivalent to the problem that you are actually experiencing - instead of just stating that you are experiencing a problem.
As for the issues, I believe that all of these issues except for 7 and 8 are genuinely game-breaking, because they cause problems that can't be worked around. I don't like these kinds of issues - especially the lack of depth sorting, which (if I remember correctly) is the cause for a huge framerate drop when there are very many caves/tunnels underground and you look in their general direction, even when you're at the surface and they are all under the dirt-grass/sand/whatever.
EDIT: Actually, FPS creator never got a new version. They stopped working on it, and released it (and lots of the model packs) as open-source. Yay for free software! :D
(in the past, there were only a few free model packs; most of them had some cost to be downloaded from their online "store", but the software itself was free of charge)