Unlock Switch Hero Option:
Successfully complete ALL story mode missions to unlock the 'Switch Hero' option at the 'Pause' menu.

Unlock Venom Races:
Successfully complete ALL Story mode missions.

Unlock Medium Combat Tour Difficulty:
Successfully complete 8 easy Combat Tours after 'Hell of a Mess' (Chapter 4).

Unlock Medium City Event Difficulty:
Successfully complete 'Inexpugnable' (Chapter 6) and 10 City events.

Unlock Hard City Event Difficulty:
Successfully complete 'Class Trip' (Chapter 8) and 20 City events.

Unlock Hard Combat Tour Difficulty:
Successfully complete 12 Medium difficulty Combat Tours.

Unlock Insane Combat Tour Difficulty:
Successfully complete ALL Hard difficulty Combat Tours.