Drop game polish

[dorkster]

Initial implementation: #41

There is a list of possible improvements on that PR. I will list the ones I think are priority:

• music
• background
• animations
• sound effects
• held block display
• mouse/touch controls

[cxong]

ViRiX has opened two more tracks of his this year: https://opengameart.org/content/upbeat-visual-novel-music https://opengameart.org/content/cheerful-upbeat-tune