Wendy Witchcart is an old human witch who rides around in a specialized rail cart on an island that she claims as her own, and is the main villain who turns the islanders into crystals. Miles "Tails" Prower, better known as Sonic the Hedgehog's sidekick, is afraid of seeing a world filled with the witch's rails and decides to stop her on his own.
While Sonic collects rings to protect himself, Tails carries a special ring that he can throw like a boomerang or grab things with. Since collected crystals cost time on the score tally screen, the author simply ignores them all.
There is an alternate YouTube stream featuring commentary by the author via annotations.