Full list of parts and how to use them:
Quad Legs: Slow, 75% armor, press SPACE to become a stationary turret that deals double damage
Biped Legs: Medium Speed, 50% armor, press SPACE to dash
Tread Legs: Very fast, 0% armor, no ability
Plasma Cannon: CLICK to fire, if you can fire fast enough it has very high damage potential
Hydraulic Sword: CLICK to swing, if you follow up the first swing with another swing quickly you can chain them together for increased attack speed
Beam Laser: HOLD to fire, starts off weak and gets stronger the longer its held down. Burns out and needs to cool down after 8 seconds.
Gatling Arm: HOLD to fire, needs to spin up before firing
Rocket Launcher: HOLD to load up to 4 rockets, RELEASE to fire
These arms can only be obtained by trading with Goliath bots
Corrosion Cannon: HOLD to charge, RELEASE to fire OR CLICK to fire a weaker projectile. Deals continuous damage, can charge for up to 2 seconds to increase damage and time over which damage is dealt.
Grenade Launcher: HOLD to load up to 6 grenades, RELEASE to fire. Grenades are more accurate at close distances and less accurate at far distances. Can be fired over obstacles.
Laser Javelin: HOLD to charge, will fire automatically. Extremely powerful laser weapon that can pierce multiple enemies and travels through obstacles. KNOWN BUG: Does not affect the boss.