Play as Drew or Mina:-  Hold L + R + B + Right at the character selection screen.

Complete level quickly:-  Hold Right + R + L + A during game play.

Exit Level  -  On the pause screen, you can return to the level-select screen by pressing L + R + A.

Invincibility  -  On the Pause screen, hold L + R + B and press Down, now your energy will refill continuously.

Gameshark codes

Enable Code (Must Be On) 0000D64D 000A  10000C98 0007
Invincible 330007DA 0010
Infinite HP 330007E0 00FF
Max HP 33000840 00FF
Max Force 33000843 00FF
Max Attack 33000842 00FF
Infinite Keys 330007D0 00FF
Quick Charge 730007C2 0002  830007C2 0042
Start With 50,000 Atoms 73003594 0000  83003594 C350
Low Level Time 3300358C 0000
Always Shot Modifier Codes
Reflect 330007FC 0010
X-Ray 330007FC 0020
Press A+B+Up To End Level 74000130 03BC  3300076C 000D  74000130 03BC  33000770 0001
Quick Score Tally 33003552 0003  33003556 00FF
Open All Levels 330034CF 0024
Unlock Extra Characters 330035F4 000F