So Hirokazu Yasuhara is speaking right now at Digital Dragons in Poland, and there he is revealing a whole bunch of development stuff about Sonic games. @necrosofty is posting stuff from it on Twitter. Unused overworld maps from Sonic 2, showing unused zone names: Source Sonic 2 being originally planned to have time travel. At the time Yasuhara didn't know Ohshima was doing the same thing with CD: Source Design sketches from before Sonic 1: Source A note on the last one: the Twitter user is trying to convince Yasuhara to share more of this stuff on Twitter. You should retweet his tweet to show people want to see more.