Hard difficulty:
complete the game under the Normal difficulty setting to unlock the hard difficulty setting. Enemies will inflict double damage and traps are faster.
OmniMax mode:
Complete the game under the Hard difficulty setting to unlock OmniMax mode. In Omnimax mode you will have unlimited Omnitrix energy.
SuperHero mode:
Complete the game under the Hard difficulty setting to unlock SuperHero mode. In SuperHero mode you will have unlimited health, but still can be harmed by hazards.