Enter these in the ‘Cheat Menu’:

JFFSPNGDNBRG  	INFINITE LIVES
HTSDNM		GALLERY
LRNMSNHR	SHOW CREDITS
MGRLSGTM  	ALL WEAPONS
RHNSRLL 	UNLIMITED AMMO
MBRNKLSN  	SPIRIT MODE
HFLLTHSH 	TINY ENEMY
PRMSHN 		BIG HEADS
LLSNMRTN	INVINCIBILITY
BGGNTSS 	DISCO MODE
PTLFGNDS 	LEVEL 1 WARP
QTMBGS 		LEVEL 2 WARP
GTMNDSBF 	LEVEL 3 WARP
NCPGHM 		LEVEL 4 WARP
RSTPDFRPL	LEVEL 5 WARP
BGRSD		LEVEL 6 WARP
NBCD		LEVEL 7 WARP
LFRRSPR		LEVEL 8 WARP
CRCDND		LONGHUNTER WARP
CTNTSCND	MANTIS WARP
THSFNDNT	TREX WARP
HSTSMN		CAMPAIGNER WARP
TRNTNNQ		ALL MAP
KNTSFSKS	FLY MODE
CRLSFNDNGS	PURDY COLORS
DGHTTSRS	ALL KEYS
TKMDKK		SHOW ENEMIES
GSRCGKFS	QUACK MODE

Thanks to Revolution readers Kauza and Jimmy Tjörnvik!