In the level where the boss is playing an old phonograph, find the three hidden watermelons. They are found in the following locations: just before going down to the wall of adobe buildings on the left; hidden in a deep gully; and on top of the mountains. Shoot all three of them to play a shooting gallery mini-game.
Hidden runestone
Start the level where you have to go to the log mill to kill the "Twins". Enter one of the rooms in the three gin distilleries at the start of the level that has a "table" constructed from a wood plank laying across barrels. Use dynamite to blows up one of the walls in that room to find a hidden area. Inside is a glowing purple Runestone.
Various Codes
During gameplay press TAB, after type one of the following codes:
Effect - Code
God Mode - God
All Weapons - AllWeapons
Max Ammo - AllAmmo
Max Ammo and All Weapons - Loaded
Flight Mode - Fly
No Clipping - Ghost
Infinite Oxygen - Amphibious
Teleport to Crosshairs - Teleport
Third Person View - ViewSelf
Invisible to Enemies - Invisible True
More Codes
Hit escape during the game. Pause menu will appear. Now hit tilde (~) to show the command prompt. Enter any of the following codes. You wont be able to see the codes as you type them. You must re-enter them for each level.
Effect - Code
God mode - god
All weapons - allweapons
Maximum ammunition - allammo
All weapons and ammunition - loaded
Flight mode - fly
Disable flight and no clipping - walk
No clipping - ghost
Stay underwater without damage - amphibious
Teleport to area currently looked at - teleport
Scale player size - changesize (number)
Restore default player size - changesize *
Set player speed - setspeed (number)
Set maximum jump height - setjumpz
Set gravity - setgravity (number)
Set slow motion factor - slomo
Set camera to behind view - viewself Camera and pawn not rotated together when True - freecamera (true or false)
Toggle invisibility - invisible (true or false)
Possess a pawn of indicated class - avatar (class name)
Summon requested class - summon (class name)
Kill all pawns andenemies - killpawns
Another hidden runestone
There's another hidden runestone in the chapel in the cemetery level. Go into the back room and again: Shoot the wall beside the leaning table to open a secret room.