SRB2 is a fangame made by Sonic Team Junior. It is based on doom legacy engine and you play as Sonic the Hedgehog, Knuckles the Echidna, or Tails the Fox. Darkspine sonic is a new form of Sonic which first appeared in Sonic and the Secret Rings (formally Sonic Wildfire) Srb2 also features a Mario mode which is unlockable. But, I have no idea about the plumber XD part of your question.
Chat with our AI personalities