Level Code
Phase 2.1 - CBYXYC
Phase 3.1 - XABXAB
Phase 3.2 - AZCBXC
Phase 4.1 - YYBBCY
Phase 4.2 - BAXCXX

Invincibility
XBABYX

Secret Level
After mission 1, phase 2 is completed, head south, into the canyon. You’ll find another exit.