These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The Stage Clear Credits is quite a beautiful tune tune. It is just called "Special Ending 4", but it is quite heartwarming as well. It also has the background set randomly.
The ending of the Game Boy version of Tetris Attack. A most emotional/heartwarming chiptunes, especially everything after 2:00.
The more calm, beautiful example of this is the SNES Version: whether it's a young fairy girl or a cute dino dragon running on a rainbow, it really sets up your mood. Especially after the clearing the hard mode.
Broken Base: Planet Puzzle League for the DS allows you to use the stylus instead of traditional controls. You can guess how this turned out with fans.