From Sonic Retro
January 31 (
- 2004 — "The Dam Scam", the 18th episode of Sonic X, airs in North America.
- 2008 — Super Smash Bros. Brawl is released for the Wii in Japan, featuring Sonic as a guest fighter.
- 2013 — Sonic & All-Stars Racing Transformed is released for Steam in North America, Europe, and Australia while Sonic & Sega All-Stars Racing is released for the Mac App Store in North America and Europe.
- 2015 — "Cowbot", the 11th episode of Sonic Boom, airs in North America.
- 2018 — Sonic Adventure Official Soundtrack Vinyl Edition and Sonic Adventure 2 Official Soundtrack Vinyl Edition, both vinyl albums, are released in Japan.
- 2019 — Sonic the Hedgehog, Sonic the Hedgehog 2, and Sonic the Hedgehog Spinball are released for Mac OS X and Linux devices through Steam while the Wii Shop Channel is shut down, rendering all Sonic games on the store unavailable.