Hold Extra Grenades:
Normally, you\'re only supposed to hold 6 grenades
but when you have a grenade thrown at you
you can pick it up and throw it again.
Instead of throwing it you can keep it for later
by pressing the minus button a second time after picking up a grenade.
There\'s no limitation of grenades when doing this.
Unlock All Extras:
At the chapter select screen, hold +, and press Right, Right, Left, Left, 2, 2.
