Forsaken has levels set up in a branching manner. If you beat level 1 in two minutes and 30 seconds or less, you'll go to the medium difficulty levels branch. Finish Level 1 in one minute and 40 seconds or less and you will go to the hard difficulty levels branch.
There are two other levels in which you can "warp" from the Medium path to the Hard path. They are "Catch the Orb" and "Power Down" -- (both found in the Medium path). In Catch the Orb, you'll have to chase down the third bounty hunter within the game (don't pick up the fake golden orb of matter) and once you destroy the hunter, he'll drop the real golden orb. Get it, and return to the starting point -- now you will be able to play the Hard path.
In Power Down, simply make your way to the end of the stage, (pick up a resnic reanimator -- extra life), hit all three switches, then destroy the enemies that come out of the now unlocked doors. Once this is done, the thing in the middle will lower it's protective armor, and then go to the front of it and blast the Red "eye".
(The other way to remain on the medium path, is to blast the eye at an angle while it's armor is still up.)
Codes
When the game says "press start" enter these codes:
Turbo Crazy Mode: B,B,R,UP,LEFT,DOWN,C-UP,C-LEFT.
Psychedelic Mode: A,R,LEFT,RIGHT,DOWN,C-UP,C-LEFT,C-DOWN.
Gore Mode: Z,DOWN,C-UP,C-LEFT (4 times),C-DOWN.
Extra Lives on the first Hard Level
First beat the fist level in under 1 minute 40 to access the hard levels. Next do the first hard level. Fly up and right down the hall. Bump the two or three guys out of the way and fly into the tunnel straight across the room. Get the one up and go back. Go down the tunnel straight down. Keep going towards the last green thing you have to protect. In the room right before the tunnel to last green thing is four square holes. Down one of the holes is a second free man and some sheilds and some weapon energy. Simply stay there till it says mission failed and you will be one man richer.
One Hit Kills
When the game says "Press Start" enter: B, B, B, L, R, Left, Down, Down.
Unlimited Titan
When the game says "press start", enter A, B, L, Up, Up, C-Up, C-Up, C-Right. If done correctly a message will say "Infinite Titan missiles".
Access Hidden Levels...