In the NEW GAME menu, type the following as your player name to
skip to levels 2
through 19:

mayday
victory
challenger
azimuth
revealed
stoneage
warfare
oxygen
skyhigh
sunshine
blowup
neuftrois
baracuda
giveaway
waterfall
seventeen
neartheend
y2k

These codes'll help too, they should be typed player name:

dogmode - activates god mode control in in-game cheat menu
stoneskin - activates infinite shield control
pianist - activates enemy shot control
boooost - activates infinite boost control
kinput - activates string control in the CHEAT menu, in which you
can type
reflux - infinite Flux Beam ammo
greens - infinite Phase Shift Cannon ammo
firecrackers - infinite Hellfire ammo
nails - infinite Titans Hammer ammo
volcano - infinite Magma Cannon ammo
lightning - infinite Elctronic Laser ammo
staystill - infinite Stasis Cannon ammo
listener - infinite Sonic Cannon ammo
bloody - infinite Plasma Cannon ammo
stormfire - infinite ALL WEAPONS ammo
getridof - infinite ammo on no weapon