To unlock the Trogdor 3-Dungeon, beat the game and then go to the Trogdor Machine.
Redcoat Ghost patrol:
Do the following to repeatedly gain 100 points. After Trogdor get out of the machine go to the House of Strong. Help the four colonel ghosts to get the ghosts out of the hose. Go outside to the field and shoot the Redcoat Ghost with the light musket. You will gain 100 points and this can be repeated.
After Trogdor is out of the machine and the ghosts leave the House Of Strong, go to a redcoat ghost found somewhere in the field. Take out your light musket. If you miss it, The Cheat will come out of nowhere and laugh, similar to how the dog on Duck Hunt appeared.
The Ruins of Burnination - Blur the lines of the 8-Bit world and Free Country, USA.
The Mainframe - Find your way into the Mainframe.
The Peasants; They Love me! - Get the Peasants to join your party.
I Have the Power! - Obtain the Trogsword.
Collectible Achievement Monger - Find all 12 collectibles.
Cosplay Master - Find all costume pieces.
The Ghosts of Our Forefathers - Free all four colonial ghosts.
...Has Joined Your Party! - Acquire all members for your party.
Burninating the Peasants - Burninate all of the Peasants.
They Loose Value if Opened - Collect all classic Videlectrix game boxes.
Collect All Our Playsets and Toys! - Collect all Cheat Commando Traction figures.
I'm A Good Graphicketeer! - Collect all Videlectrix Good Graphicketeers Cards.
SBCG4AO MMORPG!!! - Achieve the highest possible Awesomeness level.
Dragon-Man Slayer! - Defeat Trogdor.