Enter these codes at the cheats menu:

LLSNMRTN
Invincibility

JFFSPNGDNBRG
Infinite lives

MGRLSGTM
All weapons

RHNSRLL
Unlimited ammo

TRNTNNQ
All maps

DGHTTSRS
All keys

TKMDKK
Show enemies

PTLFGNDS
Level 1 warp

QTMBGS
Level 2 warp

GTMNDSBF
Level 3 warp

NCPGHM
Level 4 warp

RSTPDFRPL
Level 5 warp

NBCD
Level 7 warp

LFRRSPR
Level 8 warp

CRCDND
Longhunter warp

CTNTSCND
Mantis warp

THSFNDNT
Trex warp

HSTSMN
Campaigner warp

HTSDNM
Gallery

MBRNKLSN
Spirit mode

HFLLTHSH
Tiny enemy

PRMSHN
Big heads

BGGNTSS
Disco mode

KNTSFSKS
Fly mode

CRLSFNDNGS
Purdy colours

GSRCGKFS
Quack mode