Three Dollar Quill

I had a packed day today, so I'm going to go even lower-effort!

I've run across various bits of software that sound interesting, but I haven't used, or haven't used them to their fullest potential. Maybe it would be handy to have a list.

• Mindforger: I ran across this oddly Spider-man-themed notebook app reading someone's posts on Mastodon. Looking at my current horrifying pile of Sublime Text windows, and the fact that I moved most of my desktop items into a folder called "a lump under the carpet", I'm interested in more organized note-taking, which this sounds like it could maybe offer? I don't have a good idea yet of what kind of initial investment is required to get started.
• Alloy and TLA+: I'm putting these together even though they're distinct software, because I don't intuitively grasp the differences between them on various axes. They're both tools for working with specifications of system behavior, and verifying that properties hold, and generating counterexamples if not.
• pijul: I've mentioned pijul before. It's a version control system that uses a different underlying model than git or mercurial, which has various claimed benefits. I've only been able to install it since the latest release came out, and I had problems using commands recommended by the documentation, so I kind of bounced off it for now.
• BeeWare, Kivy, and LiSE: Another set of somewhat related things: BeeWare, I heard of recently, and Kivy, I heard of earlier. Both are cross-platform toolkits for user interfaces in Python. LiSE is a game engine built on top of Kivy. LiSE sort of sounds like it would be good for some of the game ideas I've had, but I'm not really sure.
• Hypothesis: I've used Hypothesis to generate tests some, but not enough for my tastes.
• Cosmic Ray: I haven't used this any, but it sounds interesting. It's for mutation testing, which basically tests the usefulness of your test code.
• While I'm mentioning tools for evaluating tests, the Coverage alphas, which provide the "who tests what" feature.
• Machine learning libraries. Not listing any because there are so dang many, it seems like.
• PuzzleScript: I've used it some; I created a set of thematically-motivated rules for a game, then never made any levels for it; dunno if that's still accessible, and I think I also made a tic-tac-toe game, which was great because previous attempts have fallen to feature creep.

Probably other stuff I'm forgetting right now.

PS: I was forgetting fantasy consoles, in general.