Serious Sam

Cheat mode:
Click and hold the Left Analog-stick and press Black, White, Y at the main menu. A "Cheats" option will now appear at the main menu.
LKA1RN.

After enabling cheat mode, press Start during game play to access the cheat menu. You can restore you lives and ammunition to avoid dying.
Adam P..

Developer cheats:
Click and hold the Left Analog-stick and press Black, White, Y(3) at the main menu. This will unlock the "Cheats" and "Developer Cheats" options. The "Developer Cheats" will allow you to go to certain checkpoints.
ToppDawgGTK.

Hidden level:
Destroy all the statues in the Valley Of The Kings level.

Hint: Defeating the final Boss:
After going into the great pyramid, find the obelisk room. It will then rise. Keep walking around until you see an FMV sequence. You will then go to the place where the Boss climbs up the wall. Beware -- this Boss has the most powerful spells and weapons. After he/it shoots, run to the jump ramps. Jump/boost through the power rings clockwise, and when you are next to the jump ramps, preferably by the backpacks, start unloading with the Lasergun. That weapon will drop him down to a quarter of his health, but only after 800-1200 pulses. Note: He can regenerate health.

When at the Great Pyramid and the door has not opened, pull out your canon and start shooting the Boss in the head. Take out your minigun frequently to take out Kleers, Biomechs, Werebulls, etc. Then, when he is down to red, go inside the pyramid and look up. There are four triangle objects that light up and make strange noises once you jump through the ring things that have lights in them. To activate the teleporter you must use the super jumps (all four) and you will automatically jump through the ring things. However, you must make sure that the Boss is on the lighted up center. Once you have jumped through all four, look up and you should see four blinking triangles. This will take some time, so make sure you have him in the lighted up circle in the middle of the pyramid. If he is still in red when the teleporter is on, and it hits him, he will die.

Hint: Binary counter:
In the Great Pyramid stage, just before you enter the pyramid, you may have noticed a panel above the entry with alternating I's and O's. This is a timer counting down in binary. The timer starts at 1,023 and goes down from there.

Hint: View programmers:
In the first level, turn around and head down the ramp. Then, go right and turn towards the direction you are supposed to go. You should see a door. When you enter, you will encounter many big headed people that represent the game's developers. Also, if you go down the path that leads to the desert, many big red Biomechs will appear.

There is a second group of programmers in the level. From the start of the level, go down the first ramp, make a left turn, and look for a door that will not open. If you can find a secret rocket launcher on this mission, use it to destroy the door and release the second group of fans.

On the "The Bridge" level, after awhile into the level you will find a trail of +5 health pills. At the end of the trail there is a Kleer Skeleton and a small building. Go inside and get the Gold Cross. Next to the building there are five graves. Press Use on them. They will open to reveal five big-headed people that resemble the programmers. They are the same as the ones in the first level except that they have horns. When you leave them alone, they will walk around like zombies with their arms out saying, "Come to daddy!" or something similar. When you walk up to them they will say, "Hey, wait!" and wave at you.
Stephen Unwin.

Enable the "Developers cheats" code. Go to Sierra De Chiapas. When the level starts, pause game play and go to developers code #108. This will teleport you in front of a wall. Use your rocket launcher to destroy the wall. Fans with halos (or the Cro Team with halos) will walk out. They will say something about boxes (these are the people that died in the intermission sequence before this level). Wait until they are all out, then walk through. Keep going until you see a wall. The wall will open. Go through and wait until you see a person walk on stage. Listen to him, then look at the picture on the wall. Note: You can also pick up the ammunition.
Blinkfsas101.

Hint: All characters:
When you play in one player mode, you will get Serious Sam. After the first level loads and saves, exit. Go to one player mode and start a new game by pressing Y. A messed up name will appear. Do not delete that name; just select "Done". Allow the game to load and save, then exit and go to one player mode. If done correctly, Serious Sammy should be there. Keep doing these steps until you get all the charcaters. Note: When you get Serious Sam 2, do not select "OK"; there is no difference.
Thelazzyboy49.

Hint: Fly around:
Enable the "Cheat mode" code. Go to the Alley Of The Sphinxes level. When there, instead of going straight into the level, turn around and head for the mountains. After a while you will begin to lose health very fast. Give yourself full health when you are in danger of dying. In a short while, you will get to the top of the mountain and stop losing health. You may want to get full health because you will lose about 30 when you fall to the other side. You will now be in more desert. Keep running for about twenty minutes and you will walk off the desert and enter an area that looks like all sky. While here, when your gun moves it looks strange. When you slice your knife around, the whole screen will get covered by an image of it. The best part about this area is that you can fly. Hold Jump to do so. You can travel anywhere in the level. To land, hold Crouch.
Comix6190.

Mental mode:
Successfully complete the game in Serious mode, then start a new game. Mental will be fading in and out under Serious. In Mental mode, all the enemies will appear and disappear.
This code has been reported as inaccurate. Please submit any corrections or verifications.