To unlock Challenge mode, beat the game. In challenge mode, weapons can be upgraded to level 10 and the enemies are more difficult.
To unlock RYNO IV, collect all Holo-plans.
To unlock RYNO 4Ever, fully upgrade RYNO IV in Challenge mode. RNYO 4Ever can be purchased from a weapons merchant for 50,000,000 bolts.
Climb any wall:
Use the Razor Claws to climb almost any wall. Go up to the wall and High jump (keep R2 held), then attack the wall with the claws, and quickly jump again.
To refill your health, go to a nearby vendor and your health will be refilled when you exit it.
20x bolt multiplier:
To get 20x bolt multiplier, in challenge mode, go to the Battle Arena on Planet Mukow. Select the “They Were On Sale” fight. When the battle starts use a Mr. Zurkow and start throwing the Nano Bugs. Use the Pyrocitor to kill what is left. Do this three times to get 20x Bolt Multiplier.
Convict Ratchet skin:
To unlock the Convict Ratchet skin, during gameplay press pause and go to “Extras”