Sonic Adventure
Image: Sega

As everybody is busy elsewhere celebrating 25 years since the release of the Sega Dreamcast in Japan, Satoshi Okano, a former Sega of Japan artist, has started publishing a ton of incredible, previously unseen concept art from various Sonic the Hedgehog projects over on Twitter.

Satoshi Okano got his start at Sega working on Sonic Jam, where he was responsible for the promotional art, as well as helping to name the project and designing a new "cutting-edge" version of the Sonic character for the Saturn era. He was then later among the four artists who participated in the internal competition that was held within Sega to find a new look for the character ahead of his debut on Dreamcast — a contest that was eventually won by another Sonic artist named Yuji Uekawa.

The images Okano posted on Twitter include early sketches for various environments that made it into Sonic Adventure like the Mystic Ruins and Egg Carrier, drawings for the buildings from Sonic Jam's 'Sonic World' bonus stage, the Sonic-themed cover of issue 58 of the Japanese Sega Saturn Magazine, and his losing entry in the Sonic contest. It's a true treasure mine that any self-respecting Sonic fan will want to sift through and offers a fascinating glimpse into the creation of these various projects.

You can view these various pieces embedded in the tweets below:

Also, if you want to read more about Okano's work, we recommend taking a look at this incredible feature from Sean Aitchison for Fanbyte (archived via Wayback Machine). This article credits the former Sonic artist with having a major impact on the creation of the Modern Sonic aesthetic and even features some interesting quotes from the man himself about his various contributions to the series.