After you complete the game, you can have some unique interactions with the following characters:

CHARACTER - LOCATION
Ophelia - In front of the giant cross near The Hunter
Lita - In front of Lars's tombstone in the cemetery
Rima - On top of her tower in the jungle
Mangus - On top of the large sword in Blade Henge
Infantry/Army - At the Beach Party
Thunderhogs - At the Kill Master's Lair
Fire Baron - In the jungle north of the tree island at the bottom of the last continent. He is to the left of the main road as soon as it turns, traveling south to east.
Kill Master - He is patrolling on his motorcycle on the highway north of Bladehenge.

At the part where you drive the car through a castle-like structure when the building is falling down after killing Lionwhyte and exit the second glass window after the bridge, use the machine gun on full auto from the time you can see the pink bed in front of the window. Hold it while airborne. When you land, release and it will be firing on auto without pressing A.

The man at the Mortar missions highly resembles Kyle Gass of Tenacious D.

Rob Halford plays General Lyonwhite despite his last name being Lita and Lars'.

You can ride any animal that is bigger than Eddie. To ride them, hit it with a bolt of lightning to stun it. Press Y to climb on its back. To attack while riding, press A.

-During the first cinematic where it gives you the options to toggle the blood gore and swearing, wait until right before Eddie says the line that would lead to the option of turning on or off swearing. He sees one of the band members dancing on a very shaky ledge. While that band member is dancing on that ledge, he will be chanting a song that was done in Psychonauts by a couple kids in a few parts, but more notably by Raz himself in the level where you have to face four wrestlers to get a card. At the end of each match after you defeat them, Raz did the same dance and chant the song.

-The headbanger that wears the goggles on all the Death Rack missions sounds identical to Raz, but slightly deeper.

-Early in the game, low-level troops are vulnerable to enemy Avatar harassment; make sure you watch over them and protect them whenever necessary

-Make use of your double teams!

-Don't play defensively. The game is about projecting power and taking control of territory. If you try to play defensively and stay in or by your base, you'll be at a resource disadvantage.

-If you set the beacon on a building, your guys will attack the building until it's destroyed, ignoring any incoming attacks.

-The right solo played at the right time can be devastating; don't forget you have those tools at your disposal!

To triple your nitrous power, complete all racing secondary missions.

To unlock the Spike-Quilled Axe, complete all Hunter secondary missions.

To be rewarded with a music player that allows you to change songs while driving, find the Mouth of Metal upgrade near the beginning of your adventure. In The Deuce, look for red flowers around a mettalic structure. These are entrances to Motorforge. There is one located northeast of Bladehenge and another on the northeast side of the mountain where the Kill Master lives. Play the Relic Raiser Solo nearby and you can drive in with Duece. You will be rewarded with the music player.

ACHIEVEMENT - HOW TO UNLOCK
Got a Car and a Date (15 points) - Beat "Welcome to the Age of Metal".
Start a Revolution (15 points) - Beat "Exploited in the Bowels of Hell".
Thick as a Baby's Arm (15 points) - Beat "Lair of the Metal Queen".
Hair Remover (15 points) - Beat "Battle for Bladehenge".
French Kiss Instructor (15 points) - Beat "Pilgrimage of Screams".
Chicks n' Booze n' Stuff (15 points) - Beat "Sanctuary of Sin".
Ran to the Hills (15 points) - Beat "It's Raining Death".
Fistfull of Fog (15 points) - Beat "Dry Ice, Wet Graves".
No More Tears (15 points) - Beat "Sea of Black Tears".
Groupie (25 points) - Beat Campaign mode on Easy.
Roadie (25 points) - Beat Campaign mode on Normal.
Legend (25 points) - Beat Campaign mode on Brutal.
Overkill (20 points) - Beat all hunting secondary missions.
Squeal Like a Chicken (20 points) - Beat all racing secondary missions.
Protector (20 points) - Beat 20 ambush, outpost defense, or mortar secondary missions.
Metal God (50 points) - Achieved 100% completion on the stats screen.
Serpent Samaritan (10 points) - Freed 40 Bound Serpents.
Serpent Spanker (15 points) - Freed 80 Bound Serpents.
Serpent Savior (25 points) - Freed all 120 Bound Serpents.
One Hit Winder (5 points) - Purchased 1 upgrade in the Motor Forge.
Loyal Customer (25 points) - Purchased all upgrades in the Motor Forge.
Virtuoso (20 points) - Learned all guitar solos.
Tourist (20 points) - Viewed all vistas.
Now You Must Tell the Tale (20 points) - View all Legends.
Voices From Beyond (20 points) - Unlocked all songs in the Mouth of Metal.
Flowerslave (20 points) - Summoned all Motor Forges.
Practice Bloody Practice (10 points) - Win an AI Stage Battle - any difficulty.
Iron Fist (20 points) - Win an AI Stage Battle - Brutal difficulty.
Victör (10 points) - Win a ranked multiplayer match.
Subjügator (20 points) - Win 10 ranked multiplayer matches.
Cönquerer (50 points) - Win 50 ranked multiplayer matches.
Master of the Flame (20 points) - Double Teamed with every Ironheade unit.
Master of the Tear (20 points) - Double Teamed with every Drowning Doom unit.
Master of the Blood (20 points) - Double Teamed with every Tainted Coil unit.
Armchair General (20 points) - Win a Stage Battle by yourself against the AI without attacking.
Favored (30 points) - Acquired 3,000 Fire Tributes.
Sellout (30 points) - Spent 250,000 fans - any mode.
Some Demon Flesh on your Bumper (20 points) - Slayed 150 enemies with the Deuce - any mode.
I've never touched an axe before (30 points) - Personally smote 300 enemies - any mode.
Silence, groundwalker! (10 points) - Gained 5 or more seconds of hang time in a single jump - any mode.
Six Degrees of Schafer (15 points) - Play with or against another player who has this Achievement.
Ringleader (15 points) - Trapped 15 enemies in one ring of fire with the Fire Baron's Double Team.
Painkiller (15 points) - Kill 25 enemies with the grinder of one Rock Crusher.
Dollpocalypse (15 points) - Hit 6 enemies with the explosion from a Brood's Double Team.
Euthanasia (15 points) - Hit 15 enemies with one Agony Ball using the Pain Lifter's Double Team.
Death From Above (15 points) - Kill 20 enemies with one Bleeding Death.
Coolest Thing Ever (15 points) - Jumped over a Hextadon in the Deuce.
Beast Master (15 points) - Rode every animal in the world.
Boar Bather (50 points) - Rode a Razorfire Boar into the Sea of Black Tears and live to tell the tale.
Quill Tosser (20 points) - Kill a Tollusk using only Ground Urchins.

"Hammer Of Infinite Fate" achievements
ACHIEVEMENT - HOW TO UNLOCK
Carnivore (10 points) - Run down 20 animals in the Deuce with the Coiling Maw equipped.
If You Want Blood, You Got It (10 points) - Kill 20 Tainted Coil units with the Disgorger.
Cry Me a River (10 points) - Kill 20 Drowning Doom units with the Eye of Sorrow.
Beard Beard Action Beard! (10 points) - Make out with Ophelia while wearing the Mountain Man Threads.
A Face Like a Beast (10 points) - Kill 15 enemies with a Metal Beast while wearing the Zaulia Threads.
Hammer of Infinite Fate Tourist (10 points) - Play a multiplayer game on all Hammer of Infinite Fate multiplayer maps.
Hammer of Fate Champion (10 points) - Win 10 games on Hammer of Infinite Fate maps - ranked or vs. the Brütal AI.
Whispering Rock (10 points) - Chisel four Razputin heads onto Mt. Rockmore.
Norwegian Sendoff (10 points) - Visit the grave of a fallen hero while wearing the Black Metal Threads.