Right before entering the soccer field to face the soccer moms and kids, recover your energy by kicking the tree in the small fenced area outside. The third and seventh kicks will spawn traps and enemies, so simply grab the items from the other kicks.

To unlock all levels, at the main menu, press UP, LEFT, UP, LEFT, DOWN, RIGHT, START.

Unlock the following weapons by collecting the corresponding numbers of parts and combining them:

WEAPON - PARTS
Heat Seeking Warheads - Collect 700 Parts
Hyper Plasma Ball 1 - Collect 300 Parts
Hyper Plasma Ball 2 - Collect 400 Parts
Plasma Artillery 1 - Collect 200 Parts
Plasma Artillery 2 - Collect 300 Parts
Plasma Ball 1 - Collect 100 Parts
Plasma Ball 2 - Collect 200 Parts
Rocket Launcher 1 - Collect 500 Parts
Rocket Launcher 2 - Collect 700 Parts
Shock Wave 1 - Collect 400 Parts
Shock Wave 2 - Collect 500 Parts
Spread Shot 2 - Collect 100 Parts