Play the "Desperately Saving Susan" Nerd Rescue and go to coordinates X: 479.1, Y: 488.3 to find a Xenomorph egg from Alien behind the nerd you are saving. Note: Michael Biehn, who voices the main character, was also a cast member in Aliens.
Dungeons & Dragons reference
When you need to distract an enemy, you can throw a twenty sided dice at them.
Easy "Just The Tip" achievement
Find an enemy garrison. Disable its barrier inside and try to keep some soldiers still alive. Use cyber hearts to get a Blood Dragon into the base. Allow the remaining soldiers and Blood Dragon to fight each other. While they are fighting each other, get ammunition, health, and other supplies from the garrison's vending machine. After the Blood Dragon has killed all the enemy soldiers, it's health should be knocked down a bit. Use C400 and grenades to whittle down the Blood Dragon's health some more. Use the structures in the garrison to block its beam attack. If needed, get more health from the vending machine. When the the Blood Dragon's health is brought down to just a sliver, switch to the bow. Be patient and wait for the dragon to rear back and fire an arrow into its chest. Repeat the process until its dead.
Far Cry 3 reference
Swim underwater at coordinates X: 531.2, Y: 321.5 to find a scientist next to a toilet, similar to the seasick soldier found in Far Cry 3.
Hobo with a Shotgun Reference
The 80s movie, Hobo with a Shotgun, was an inspiration for this game's creative director, and is referenced by the Summon the Plague! mission title.
Middle finger
You can give people the middle finger if you hold [Melee]. You can also press it multiple times to use both hands.
Predator References
If you ever saw the movie Predator, which starred Arnold Schwarzenegger and Carl Weathers (among others), you witnessed one of cinema's most famous handshakes. You can witness it again here, in 16-bit form, during the first five minutes or so of play. There's another reference to the film, as well. During the chopper assault sequence, pay attention to the song that plays. It is Long Tall Sally, performed by Little Richard. You might recognize it from the moment in the movie when the commando team heads into the jungle.
RoboCop Reference
The pistol that Rex carries bears a striking resemblence to the weapon used by RoboCop in the old action movies. Its burst-fire function in particular shows that connection. There are other nods to the film, as well. The weapon's description notes that it "was built and named in honor of a fallen DPD cop who fell in the line of duty fighting the creeps of the Detroit megaslums and industrial wastelands." The weapon is called the A.J.M. 9, in reference to RoboCop's name: Alex J. Murphy.
Secret Achievements
Complete the following achievements to unlock Xbox Live Gamerscore points.
Achievement
How to unlock
End Game (50 points)
Finished Final Showdown.
One Small Step (20 points)
Finished First Garrison.
Welcome to the Party, Pal (10 points)
Finished Helicopter Entry.
Teenage Mutant Ninja Turtles
Head to the coordinates X:519.9, Y:365.6, where you will find a garrison and the Predator's Path quest. Your goal is to kill turtles that have been befriending rats in the nearby sewers. When you find the turtles, you will see that their faces are painted hues similar to the headbands worn by the famous turtles from the comics and cartoons.
Teenage Mutant Ninja Turtles reference
During one of the Predator missions, Rex must kill four turtles in the sewers. You can find a pizza box in the sewers and each of the turtles are wearing colored ninja masks.
Terminator 2 References
You will find the Galleria 1991 shotgun on your adventure, and that is a reference to the movie Terminator 2: Judgment Day. In the film, there is a shootout in the Galleria mall, and the movie was originally released in 1991. Also, the Cyber-Eye ability takes on an appearance similar to the scan performed by the Terminator in the movie.
Various Achievements
Complete the following achievements to unlock Xbox Live Gamerscore points.
Achievement
How to unlock
Blood Dragon Down (20 points)
Kill Your First Dragon.
Derp (20 points)
Jump Down from 50 Meters .
Dragon Slayer (20 points)
Kill 25 Dragons.
Hail to the King (40 points)
Reach Maximum Level and Become the Ultimate Badass.
Just the Tip (15 points)
Kill a Dragon with the Bow.
Kill Them All (20 points)
Finish all the Predator's Path Quests.
Murder Nature (30 points)
Kill all the Animal Types.
Nice Like Jesus (5 points)
Finish all the Hostages Situations.
Running man (30 points)
After saving Darling, enter Combat Mode with a Dragon and Return to Stealth.
