Allow the game to idle at the mission selection screen and Pox will make various remarks.
After leaving your UFO, aim at a human and press [Y]. When you have changed into the human, the bar on the top left corner of the screen will go down. When it is all gone, you will change back into an alien. If you want to remain human, turn into a human and while walking around, scan other humans or animals to make the bar on the top left corner stay up.
Turn into a human then enable the "Ammo-a-plenty" code. You will stay human forever. You do not have to scan thoughts to get out of the human body - just press [Y].
Faster destruction in the UFO
Instead of holding [R] to destroy buildings or large objects, tap [R] and the destruction will happen faster without waiting for the recharge.
Destroying Majestic cars
Use your PK ability on a Majestic limo. Hold [L] all the time. Get a wall between you and the car then start running away from the wall until the car smashes into it. Keep running backwards and the car will eventually explode. This trick can also be used to take out normal cars and people.
During mission 3, to keep the town people happy when disguised as Mayor choose the following statements.
Tell The Truth
Convincing General Armquist
Tell A Joke
Make Empty Promises
When he asks you about the fair, say "Rowdy kids did it". Then say "Did you catch the assassin?".
If you scan a mutant a few times, eventually he will say, "1... +... 1... =... window".
Getting away from the law
Forget running away from the authorities with short legs. Use your jetpack liberally to fly away. Press [Left Analog-stick Forward] and hold [A] to boost away.
Disguise yourself as a human to help you to get around virtually undetected. You cannot be seen by anyone if you are in stealth mode, even the police and the military. When Majestic appears, never get close to them. They will bring it down when you glow red. That does not indicated that you are being jammed; it just warns you if an agent is too close to your presence. Figure out a way to take them out or avoid them. The PK is recommended as a good stealth weapon against them.
Easy collect brainstem puzzles
Enter a collect brainstem puzzle. Find out how many you need. Then, stand around extracting the brains and leave them laying there close by. When you have enough, go to the challenge and enter it. You can easily win by doing this.
Finding more probes
Probes are necessary to get upgrades faster. In order to find them all, make sure to look high up on rocks or hard to reach places. Your jetpack is essential in getting to the high places. You may have to get up on the ledge or building, then use your jetpack to fly higher to get the probe.
When you are in Capitol City, you can find about ten probes by the broken Pentagon.
When you unlock Area 42, you should see some bunkers that represent bomb shelters. They all have ammunition inside.
When you pick something up, you can control it with the [Right Analog-stick].
The awareness levels at at the top of the screen. They are four basic icons. The first one indicates that civilians are aware of your presence and its color should be purple. The second one indicates when the police are sent to investigate, and are on the scene with a yellow car symbol. The third one is a big orange star, which indicates that the military are involved. The fourth one is Majestic, a top secret government agency which has the power of seeing through your disguise and bringing you down with high tech weaponry. When you alerted to the police and the military (the orange star and the yellow police car) you can disguise yourself as a soldier for the military alert level or a policeman disguise for the police alert level. You can just use a normal civilian disguise for the first icon. You can also find hiding places or use your Jetpack to escape. For the Majestic alert, disguise yourself as one of them, but do not get too close or your disguise will deactivate, revealing your alien form. The Majestic symbol is a big red M. Keep moving when you fight them and look for out men in black with big green guns.
Put your target (dot in the middle of the screen) on any human, and press [B]. In order to maintain your HoloBob, you must read the thoughts of the humans walking around. You can read the same person's thoughts repeatedly to keep your mental powers charged.
HoloBob when near Majestic
Majestic will not always jam your disguise if you get too close. This only happens if you are on a mission. Otherwise, you can walk about six feet away from them and they will not jam your disguise.
Better DNA value
Every chance you get, do not kill the human before you extract their brain stem. Extract their brain stem first as it will make the DNA worth more (25 instead of 10).The easiest humans to do this to are the scientists in the level with glowing cows. For some reason, if the person that is important to you dies (the person you need to abduct), extract their brain stem before you return to the Mothership -- the DNA is usually worth more.
It is rare to find humans with brain stems that are worth 50 or 100 DNA. Most humans have brain stems that are only worth 10 or 25 DNA. If you walk around Union Town, there will be humans with signs on them reading, "REPENT THE END IS NEAR". Those humans will have a brain stem worth 50 DNA, no matter what.
Mystery Agents' brain stems are worth 25 DNA points most of the time, whether dead of not.
The Psi G-Men are worth 150 DNA alive and 75 DNA dead.
After you beat the game all brain stems will be worth more when you use the anal probe:
Citizen from 10 to 15
Cops from 25 to 40
Repent men (Union City) 50 to 75
Army from 25 to 40
G-Men from 50 to 75
This will help to buy the expensive final upgrades.
When Pox has you take out the President, just run up, extract his brain. and take it. When you do this you will get 200 DNA. That is the most you can get from a single human.
To get more DNA from humans, first use Hypno on them. For example, using Hypno on a town crazy (the one with the sign) can result in 200 DNA.
To probe a Majestic Agent, cycle to your anal probe and charge it. Then, shoot the agent. Do this three times and the agent brain will pop out. It is worth 75 DNA each time.
Shoot a human (normally worth 25 DNA) with the anal probe a few times without charging it, then shoot them with full charge. Their brains may now be worth 50 DNA instead of the usual 25. This is best used at Tunipseed Farm and Rokwell. Farmers and cowboys work the best. This does not always work, and never works on army men and Majestic Agents.
The best way to super charge DNA is to use your Zap O Matic. Zap the person just before they die. Then, hold [L], target the person, and rapidly tap [B]. Their brain should now have be super charged DNA.
During the mission where you are supposed to assassinate the President, instead of shooting him or blowing him up, take his brain. It is worth 200 DNA.
When you are in Capitol City, go to The Octagon (the place where you fight Silhouette). There should be G-men who are glowing green. They are radioactive. Extract their brains to get about 150-300 DNA.
If you need extra DNA or you are running low for an expensive upgrade, go back to the Turnipseed Farm level. Extract as many brains as desired. The Anal Probe Gun is a good weapon for this. Its much easier to use than rapidly pressing the [B] to extract the brain stems of humans, as one charged shot from the Anal Probe will make their brains explode. You need three successful hits on Majestic Agents, two successful hits on the soldiers, and one hit for the policemen. Normally you can choose to extract your brain stem with the probe button ([L]) and tapping [B] rapidly to extract DNA faster. However this is not an effective tactic to use as Majestic Agents and soldiers take more concentration to extract their brain stems. Forget the concentration meter and use the Anal Probe Gun. To aim, use the [Right Analog-stick] and place it over a human. Then, hold [R] to charge up the Anal Probe Gun. Release [R] to fire at the selected target. One shot is all that is needed to take down some humans, but others may require more. However, you have unlimited energy with the weapon.
Brain extraction and cortex scanning is best done with the anal probe, and not the concentration meter. A fully charged blast from this weapon is all you need to kill them. Make sure it is a direct hit. You can adjust your aim by using the [Right Analog-stick]. You can do it with the extract ability, but you must remember that the Majestic military and the police require a lot of concentration to snatch their brain stems. The anal probe weapon should prove useful wit them. Cortex scanning can refill the concentration meter and will give you a longer Holobob. Be sure to scan some humans to keep it fully charged.
It you levitate a person for a long time, they will die.
While playing as Crypto, pick up someone using PK and throw them up in the air (do not push them). When they come back down, shoot them with the disintegrater ray. They will freeze in the air and melt, showing their skeleton.
Lower brain juice meter
When you are in the form of another person, to make you brain juice meter go down, read other people's thoughts.
When anal probing someone, TK them just to lift them up. Do not push them or slam; just tap [TK] and release. This should put them on the ground. While they are on the ground, charge up the Anal Probe fully. When they first start to get up, release the Anal Probe. The brain stem will come out without them running all over. Note: this works best on Turnipseed Farm.
When trying to hypnotize people, rapidly tap [X].
Extract DNA faster
While extracting a person (alive or dead), tap [B] quickly. You will get their DNA easier. This is useful against the M Agents and Psi G-men.
Extra jet pack distance
When using all the power in your jet pack, repeatedly tap [A] and you can get to farther distances.
Examine the back of the Jetpack when you first take it out. You will see three green rectangles. They will turn red and act as a battery gauge. That is why you cannot fly for very long.
Fly after Jetpack has run out
To fly after your Jetpack has run out, quickly tap [A].
Enable the "Bulletproof Crypto" "Ammo-A-Plenty" codes while on your saucer. It will not become damaged or lose ammunition.
Allow the game to idle. Eventually the screen will turn black and white and elevator music will play in the background.
Enable the "Deep Thinker", "Bulletproof Crypto", and "Ammo-A-Plenty" codes then get all of Crypto's upgrades. After this you can turn into a human and walk around TK'ing everything.
Learn Silhouette's gender early
When in Area 42, scan the minds of the Majestic Agents. Eventually, one will have a thought that reveals that Silhouette is a girl.
Ride the Washington Monument
Find the monument, then throw cars at it until it breaks into two pieces. Get on the long pointy piece, PK the middle, and try to stay on.
Get on Santa Modesta tower
To get on top of the Santa Modesta's SMCBS TV station towers, get on top of the station's roof. Then, jump onto the satellite dish and from there, to the slim post. When on the post, jump and use the "Extra jet pack distance" hint to get to tower 2. From tower 2 you can also go to the other tower. From that altitude the police, army, and Majestic cannot see you. Use the Ion Detonator to blow them up. This is best done when aiming down before jumping. You can then see where you are landing.
When you are in Santa Modesta, go into your ship and cycle to the "Abducto Beam". When any form of car is directly underneath your ship, abduct it and go near one of the bigger buildings and keep going. The car will remain against the wall of the building as you go along. When you keep moving, the car will come at you fast but will not hit you. As the car comes at you, release the "Abducto Beam". The car will go flying through the air. This also is an easy way of getting cars to explode against the tall building.
When you have to defend the radio towers, you will get to use the atomic blast in your space ship. Be very careful. If you shoot too close to the towers it will bring down there health even more.
Getting a lift
Enable the "Bulletproof Crypto" code. Go on top of a car (military trucks and tanks work best). Aim your Ion Detonator at the vehicle. Detonate it and you will be shot into the air. You can use your jetpack to fly away.
Pound cars into the ground
Pick up a Majestic car then slam it down on a pedestrian car. It will eventually pound it into the ground.
The more you move, the harder it will be for your enemy to it you. Being a stationary target for the enemy is not a good idea. Make it difficult for your enemies by moving side to side. This also works with the shotgun farmers. It is also the best way to fight the Majestic and the military soldiers with rifles. In the saucer you must strafe out of the way. This can save Crypto's life. Avoid the heat seeking missiles. When you see one locking on, take evasive action by moving to the side. It will miss you. This technique requires some practice.
When you are in Capitol City, scan a scientist and eventually you will hear, "I mustn't be late! They're waiting for me in the test chamber! Oh wait, wrong game." This is a reference to the start of Half-Life.
Pinky And The Brain reference
In the final mission, scan Silhouette's mind. Eventually she will think "What was I doing? Oh yeah. The same thing I do every night. Try to take over the world!".
Plan 9 From Outer Space reference
Halfway through the game you will experience a level where you go to the drive-in to switch films with the one that is showing. Watch what is showing before you switch films to see that the film is Edward D. Wood, Jr.'s Plan 9 From Outer Space.
Village People reference
Scan a cop in the Santa Modesta area and you will eventually hear, "If only I had a cowboy, an Indian, and a construction worker".
If you scan a Psi-Mutant a few times, he will say "Algernon... Good mouse... Smarter... than... Charley". The Psi-Mutant is thinking about the book, "Flowers For Algernon".
Glitch: Extra robot arm
When done with a mission at the capital city, enable the "Deep Thinker" and "Bulletproof Crypto" codes. Go to the bridge that goes to the octagon. Attack the people to get the robots to attack you. Use the mind control on the robots and lay them about over the edge. You can see a robot arm pulling the robot into the water.
Glitch: Attack Of The 50 Foot President: Missing sounds
During the Attack Of The 50 Foot President level, you will not have any sounds for your weapons.
Glitch: Turnipseed Farm: Water under the road
Use your TK power to levitate a chicken to go over to the road. Go to where the gate leading into the cow pin is found. Then in the middle of the road outside the gate, slam the chicken into the ground. Holding [Down], walk to the end of the road dragging the chicken. Make sure you are holding [Down] so that the chicken is constantly being pushed into the ground. You should see a splash and the chicken will go beneath the road. Do this a few more times if you do not succeed the first time.
Glitch: Floating body
Use your telekinesis to lift a body into the air and put it on top of your saucer. Make sure the body is on the saucer so that it does not fall off. When you get in the saucer and fly away, the body will still be floating in mid-air.
Note: Enabling the "Deep thinker" code is recommended. Use Holobob, then find a truck with a wooden bed at the back in Union Town. PK it to make it stop. Do not blow it up. Find a human and kill him, but do not disintegrate that person. Put him or her in the bed of the truck. If you are lucky, the truck will blow up or move on. The human will float in mid air. Cars, trucks, and other humans will not bring the human down. Only PK will bring the human down. Disintegrating will also work. Note: This may require a few attempts.