15th Anniversary Special is the 27th overall edition of Sonic the Comic Online. Released on the 29th May 2008, at STC Online, the issue marked Sonic the Comic's 15th birthday and contained one original story, several features and a large number of wallpapers. The cover was a variant one, alternating between ten different designs.
The Elephant in the Room is a complete story by Tom Huxley, Adamis and Mike Corker. The story is a questionable one, starring Cedric the Elephant, one of the unseen Freedom Fighters. The anniversary story showed Cedric appearing in many of Sonic's classic adventures, giving him support and advice. In the end, he advises Porker Lewis to live on the Floating Island, stating that most people don't even know he exists.
In this issue's Control Zone, an original model Megadroid remembers things that made Sonic, Sega and STC so good over the past 15 years - the Mega Drive, merchandise, the Sega Bus, the fortnightly Sonic the Comic and the two cartoons on Channel 4. He then goes on to state that Sonic is still alive and well, thanking all the Boomers and Humes who kept him alive.
The Data Zone is a major recap of all the recurring characters over the year. Heroes featured are Sonic, Tails, Amy Rose, Johnny Lightfoot, Porker Lewis, Doctor Kintobor, Knuckles, Tikal, the Chaotix Crew, Morain, Captain Plunder, Ebony, Shorty the Squirrel, Tekno the Canary, Norris Wimple, Fabian Vane, the Eternity Ring, The Flock, Big the Cat and Police Chief Bodger.
The page then goes on to list villains Doctor Robotnik, Grimer, Super Sonic, the Drakon Empire, Metallix, Chaos, the Marxio Brothers, Doctor Zachary, Nack the Weasel, Trogg, Megatox, Commander Brutus, The Plax, Max Gamble, Metamorphia, Colonel Granite, Vermin the Cybernik, D.R.A.T., Windy Wallis, Cam and Bert, Nutzan Bolt, The Family, Percival James Kane, Vichama, Rouge the Bat and, finally, Shadow the Hedgehog.
The story so far also covers the entire STC run, stating: "The evil Doctor Robotnik tried to conquer Mobius and Sonic stopped him. Robotnik would eventually win and hold Mobius for years, only to fall thanks to Sonic, his Freedom Fighters and their allies. Mobius has been free for years but Sonic and his gang continue to defend it from the hundreds of threats against it!"
Being a special issue of STC-O, there are many posters, this time focusing on STC's past. The leading posters are the variant covers, provided by a multitude of STC-O artists:
- Mike Corker
- Matthew Allen Smith
- Jin Chan Yum Wai
- Zak Simmonds-Hurn
- Steve Saywood
All of the 8 variants contain an image of Sonic, with every issue of STC and STC-O in the background. There's also a poster featuring all the Sonics and another with none of them.
Apart from this, there are the usual collection of scenes; the majority are by Adamis, including 4 from this issue's strip, a scene from Smokey and the Badnik and a collection poster, featuring twenty of the characters featured in the Data Zone (as well as Cedric). Lightmare makes an appearance (Smith), a shot of Blockhead Bill, Society Max and Turbo caught between the Eternity Ring and the Omni-Viewer (Fast Ashadonic), two Megadroid pictures, the second of which featuring 3 of his models, and the final poster is similar to the covers, although this only features the previous issues of STC-O, as well as the specials and the April Fools editions.