Here's a breakdown of the disco skull #tootcart, and some commented source code (press ESC twice after #pico8 boots):
https://www.pico-8-edu.com/?c=AHB4YQbVBF7rweLRl7-B2Q9QNde-wv3BiB1Of4nuKa5-hMwq7xAHRX3-OzRl31SneecNsiDNoouCV0ijrF0pnuGmqol3wpX2RsWA4qyzzrssSS677rimyoLiuOy6bisYyVeKC4-6GD6H7yF4_ncNgrdtXuVVvoXgvYJUXWii390dnJgo9prNledYbzaN4pgrH_XU-SI_NO37-YG6qausqPvpPo4vHTgi24iNMjHh6eLULnRdv9GtqBadkDdN-Sgj_UxQdisXpFl0wExwg3GaJO26LNgo36PvsnxoqEv7rB6qFjaqxD5bAxsbQVG_iCHa9I507JCojLouKnPzpDt51WRtkQXlyM4ZYVTU53ZlHUgTDLWqKUnUDSZRFVV1lWdtJ53QVU1ZRVHrgrHgkGCsUFB6jge5IlQaUhgSGHFdekiSTLV71Z7dbu0CBZNeRyQavWQwjrJSp2Ei3thSJUhabQOloKOnBQXUQyQDVEI20rMOa7Ye6bjbTqvCt3md4q7DymxYbUHaZGVMYCSYnJjQCv_tCLG3PBMMLcmZSKcMTnrmCDWEJNgq1tQVgpuKVGVhq0oz6xinGir1GgarTMbJ1YORsFwm7bCrwjDRDaxUwwfFZ6xW02G6EpZbK0pT3cJK1TTpDSdUWRKdEG0IHQxpDRS9eTYEFa6SQ7pAIUDUQb5FqNF-uqMjZXiCykMuIaKbcMKOfSblDNoT4rm0i4O1rWjQHjtFeEOejM4Fc32WDUweFeTFTNTcdHYwdPNi-zKhcsDOKQu33NWHEgEjMxO7i3HWWmNxZEzBHGGhYZROT83WzZxmzWn90FC8oZxlFE0YKZnFmb0y6S7ZEwmw1ob1v0smgmp8qDt8cSqOJpKFoakqUj7Z3kimagURLQhJriCXXwgKjTqRAz0VAVuZMK1BQYpoYkyPQiV1u9qWrgizakfjRphHcaApk90Rr8wu3NPON2MzZ4fRcrBSTa2PqWCM6HSJdM0oiUzMPIu_g6ZtKXjgjVj0ZG95rF_pi9XdbnjCGJvGijutg8w5Aj4aCllZeqDpJsJ2cn1zzLXHhXGq3HXSzMMMTfbBdNLmSWnv4dhcm_2qys7SmkjI7AW7w-IaY2o05hnebKK0ScVS1tudmU7baG12bU2uamm2WVzSM1NV6Xup_shaTRjWXwPTdTVyQhQmNhC70KIqdjfCpp3a017IxveC1aqbKXQaVpOw0RTqhhbWGvEbBYMgmVjWwbTO3AwMhKxVYdAoJ5UD6e5QkmsJSMcVjZLA9nI3W0TFvlGWk0Fvl94NvA8Ro1xvY2t2Yk8gShtBh1CMaTpu0ibQhpJ72RlZ8FZWLnNJyLQMrC-UJYZlIrYWVAx6QQNRdszOjcyYSVE8AgJJUoqo0V-A5ZvhqMTE9EoSTKhQzVWxtxYOGJmsptIVSR_cDFGpUkjPiNrgdtMuxos7M6rmUPYRzVI0muyaZKkZCATTsqrYDUOpoh72gpxsN8uMLGgtHAU=&g=Q3Iw-ws3Kw-wq3Mw-wp3Mw-wpnQ3CQnw-wpXwA3AwAXw-wpXwA3AwAXw-wpXwA3AwAXw-wpng3Agnw-wp3Mw-wp3DQ3Dw-wq3CQ3Cw-wt3Gw-wv3Gw-wvXQXQXw-wvXQXQX