I was really surprised by some libre games with really good graphics for free software, like Xonotic or Unvainquished. And also very cool projects like Speed-Dreams, that is not as beautiful but is really promising

Otherwise, very cool stuff like Kdenlive, Ardour, LMMS, Puredata, … This is a long list! 😅

Ardour is also a very good fully free (as in freedom) alternative to Reaper, if you want to experiment 😊