Source: https://www.thegamer.com/sonic-frontiers-preview-summer-game-fest/
There's another core gameplay mechanic in Sonic Frontiers that, according to the NDA I signed, I'm not allowed to talk about until June 29. If you've been following the IGN First coverage, however, it's already been revealed and widely discussed. I'll have a lot more to say about it in a couple of weeks, because it's a major part of the game and I think it's great. Here's IGN's Mitchell Saltzman describing the thing I'm not allowed to talk about.