Unlock the following options at the "Options" menu by performing the corresponding tasks:
OPTION - HOW TO UNLOCK Equipment Strength Upgrade - Collect all art. Faster Health Recovery - Collect 50% of the art. Gozerian Rookie Outfit - Complete the game under the Gozerian difficulty. This outfit will allow you to be immune to sliming. Increased Scanning Speed - Scan 50% of the ghosts and scannable objects. Invulnerability - Complete the game with all art collected and scan 100% of the ghosts and scannable objects. No Equipment Overheat - Scan 100% of the ghosts of scannable objects.