Board Thread:General Discussion/@comment-24652155-20140313063549/@comment-1784865-20140322134448

Definitely the Sonic Adventure games (1 and 2) which are conveniently available on Gamecube (as Sonic Adventure DX and Sonic Adventure 2 Battle), PSN, and Xbox Live or whatever its called.

I'm appalled that no one has suggested the originals, Sonic the Hedgehog, 2, 3 and Sonic and Knuckles! All of those are available on different consoles, including DS and PS2. It'll be good for you to see the series at its roots and see the core gameplay of the series.