From Sonic Retro
December 18 (
- 1996 — Issue #44 of the Sonic the Hedgehog comic series by Archie Comics is released in North America.
- 2003 — Sonic Adventure DX: Director's Cut is released for the PC in Japan.
- 2004 — "Sunblock Solution", the 40th episode of Sonic X, airs in North America.
- 2007 — Sonic Underground: The Greatest Hits, a CD, is released alongside Vol. 1 of Sonic Underground, a DVD, as well as Sonic the Hedgehog for the iPod in North America.
- 2012 — Sonic & All-Stars Racing Transformed is made available for digital download on the PlayStation Store in North America and released for the PlayStation Vita in Europe.
- 2014 — Sonic Toon: Taiko no Hihou is released for the Wii U alongside Sonic Toon: Island Adventure for the Nintendo 3DS in Japan.