From Sonic Retro
December 13 (
- 1996 — G Sonic is released for the Sega Game Gear in Japan.
- 2000 — Issue #196 of Sonic the Comic is released in the United Kingdom.
- 2001 — Sonic Tennis is released for i-mode 503i compatible phones through Sega's Sonic Cafe portal in Japan.
- 2003 — "Skirmish in the Sky", the 15th episode of Sonic X, airs in North America.
- 2006 — Issue #15 of the Sonic X comic series is released in North America.
- 2013 — Sonic the Hedgehog 2 is released for Android devices and iOS in Japan.
- 2017 — Sonic Forces Original Soundtrack - A Hero Will Rise and Sonic Forces Vocal Traxx - On the Edge, both CDs, are released physically in Japan and made available to download for iTunes and the Mora streaming platform in Japan and made available to download for Amazon, Google Play, and iTunes in North America and Europe.