https://www.youtube.com/watch?v=IWDjUx_fnNQ
https://www.youtube.com/watch?v=z06QR-tz1_o
https://en.wikipedia.org/wiki/Video_game_development#Game_design_document
https://en.wikipedia.org/wiki/Shoot_%27em_up
https://blog.forest-interactive.com/4-simple-reasons-why-endless-runners-are-staples-in-mobile-gaming/
https://www.youtube.com/watch?v=DxobmkRxkr8
https://www.youtube.com/watch?v=B8ttFXUgtMw
https://www.youtube.com/channel/UCqJ-Xo29CKyLTjn6z2XwYAw