The basic keys in the game are VERY easy to learn. The weapon combinations are what really make things shine, but luckily they all use the same FIRE button!!

X - jump
TRIANGLE - choose your weapon from the spinning list
SQUARE - use your wrench (attack, or spin a bolt)
CIRCLE - fire your selected weapon (or use your selected equipment item)
SELECT - map
L1 - target ranged weapon
R1 - swim faster

Spaceship Controls
X fire guns
circle secondary
square turbo
L1/R1 barrel roll
L2/R2 straighten ship

Ratchet and Clank 2 Going Commando Walkthrough