In the game Sonic Forces, which of the following was not from a previous game?

In the game Sonic Forces, Infinite is the character that was not from a previous game. Infinite is a new addition to the Sonic franchise and was introduced as the primary antagonist in this game. The other options presented in the question, such as Sonic, Shadow, and Metal Sonic, have all appeared in previous Sonic games and are well-established characters in the series.