Sheer joy is an interesting term. I like making things but I don't think that is my primary motivater for _what_ I make.
Most of my free stuff is because I think the things should exist and they are things that shouldn't have to be paid for.
Some things are just plain geek fun
https://github.com/Lerc/stackie - Makes textures using a very compact stack machine language
https://github.com/Lerc/kwak-8 - Emulator for an 8-bit computer that never existed
Some things I wanted to have exist
https://github.com/Lerc/smallcalc - A compact pop-up calculator for the Cinnamon Desktop
https://github.com/Lerc/plops - (old) A lightweight Desktop widget engine that I made when I developing for 256-512mb boxes/
https://github.com/Lerc/whio - A Javascript canvas rendering lib for beginner programmers using Globaly avalilable functions + mediaWiki plugin to run in a worker.
http://fingswotidun.com/code - A wiki usisng the plugin from the entry above. Has some introduction to programming javasctipt tutorials.
And the mad project that I come back to every couple of years to push a bit further along.
https://github.com/Lerc/notanos - A html/js login deskop for Linux.
And a lot of games.
Here's a silly one http://screamingduck.com/Lerc/LD13.html
Here's a really hard one http://www.screamingduck.com/Lerc/LD14.html
And here's one that might give your browser a hernia http://fingswotidun.com/ld21/