Start game as usual. During gameplay press [F9] to go to console,
 then enter the following cheats followed by [Enter]:

 DESTROY ALL            - Complete Level
 NEXT LEVEL             - Instant Level Skip
 GOD                    - Toggle God Mode
 SET DAMAGE 0           - Restore Health
 SET BULLET <NUMBER>    - Get NUMBER Bullets
 SET MISSILE <NUMBER>   - Get NUMBER Missiles
 SET DC <NUMBER>        - Get NUMBER Depth Charges
 LOAD LEVEL <NUMBER>    - Load Level 1-99
 RELOAD LEVEL           - Reload Current Level