Arroy keys - movement
Z - Jump
X - Weapon (rocks/plunger)
C - Switching between rocks and plunger (if you have the powerup)
Enter - Pause
If you're playing on a Xbox controller, it's:
DPad/Left stick - movement
X - Jump
A/Y - Weapon (rocks/plunger)
B - Switching between rocks and plunger (if you have the powerup)
Start/Menu button - Pause