Anniversaries/December 21
From Sonic Retro
December 21 (add)
- 1995 — Issue #32 of the Sonic the Hedgehog comic series by Archie Comics is released in North America.
- 2000 — Sonic Adventure 2: The Trial and Sonic Shuffle are released for the Sega Dreamcast in Japan.
- 2003 — "Maria no Negai, Minna no Negai", the 38th episode of Sonic X, airs in Japan.
- 2006 — Sonic the Hedgehog is released on the Xbox 360 and PlayStation 3 in Japan.
- 2011 - The Best of Crush 40: Super Sonic Songs is released for the Mora streaming platform alongside Sonic Adventure Original Soundtrack 20th Anniversary Edition, Sonic Adventure 2 Original Soundtrack 20th Anniversary Edition, Sonic Heroes Original Soundtrack 20th Anniversary Edition, and Sonic the Hedgehog CD Original Soundtrack 20th Anniversary Edition being made available for download from Amazon and the Mora streaming platform in Japan. Issue #35 of Sonic Universe is released alongside Sonic the Hedgehog 4 Episode I for the iPad in North America. Sonic the Hedgehog CD is released for the PlayStation 3 in South Korea and Taiwan.
- 2012 — Sonic Jump is released for Android devices in North America, Europe, and Australia.
- 2022 — Issue #3 of Sonic the Hedgehog: Scrapnik Island, a comic mini-series, is released in North America.