There was a bug on a door code, level 23 if I remember. Mission 2 Base 3. Still have the code somewhere, though you should be able to find it online easily enough. Played til' Mission 6 Base 5 (Level 65) Such a great game was Captive.
I remember back in Microbyte(Shop) when it was released, everyone was gathering around to help this person play it, as he couldn't get into the first base
If you like the scifi/rpg feel try System Shock 2 on the PC. Another great game.