Board Thread:General Discussion/@comment-1031724-20170323070905/@comment-477304-20170324201752

KillRoy231 wrote: Because they've already started a different continuity with the Sonic Boom games being with the TV series.

Aside from that, I didn't think it needed to be rebooted, but what they said about it not being a sequel or prequel to other games gave me the impression that it was. They've stated before that Sonic Boom is not meant to replace the main continuity, just run alongside it. Had it been more successful, it's possible that Sonic Boom would've replaced the main series, but I doubt that will happen now.

Again, there is a long list of games neither sequel or prequel to previous Sonic games but are still set in the same continuity. The only reason Iizuka specified it was a standalone title was because people thought it was a sequel to Sonic Generations.