To get the Good Ending you must defeat Smockula the Defiler, followed by The Angel of Chaos at the Live Devil Amusement Park stage
(Final Stage) while having all 5 of Smockula's body parts equipped. The body parts also count as relics which will be needed in your inventory for the I'm Thorough
achievement. These body parts include:1. Smockula's Eye
(Defeat Beautiful Queenie at Hermit Refuge Camp)2. Smockula's Heart
(Defeat Gory Mound in the Derelict Crypt at St. Sander's Cemetery)3. Smockula's Liver
(Defeat the Brainstem Boss at Camp Falconbats)4. Smockula's Tooth
(Defeat Chained Monstrosity in the sewer at Direblade Plaza)5. Smockula's Brain
(Defeat The Gorged Tumor on Brinelake Dock)
You can acquire these Body Parts by defeating specific Bosses at certain locations throughout the game. Breakable gold chests will appear after beating these Bosses, break them open with attacks to unveil a glowing body part floating in the air. You can take a picture of the body part by pressing Down on the d-pad to bring up your cell phone and hitting A while it's in focus. If you do this in Co-op, each player participating should get 1 part each after waiting a while for them to drop(upon taking a picture of them). Please see I Collected a Being
solution on how to find all 5. The billboards displayed in the background 2 screens after entering Live Devil Amusement Park will also show you their locations.
Because you need to equip 5 items at once, this means you will need to have the "Relic III" ability unlocked for your character, since it allows you to equip 5 relics at once. It should become available in the the level 15-25 range. If playing in Co-op however, this is not necessary if other players collectively have the parts. Failing to have all 5 relics equipped before facing Mortimer will result in you receiving the Bad Ending instead after beating him.
However, when facing Mortimer with all 5 body parts equipped, the body parts will spin around in the air spawning a new enemy called Smockula the Defiler. Defeat it without killing Mortimer (as they'll both be fighting you). This will revert Mortimer back to his original human state. You will then receive a more difficult extension of a Boss Form than the Bad Ending version, requiring you to progress through another stage before facing the game's Ultimate Boss, The Angel of Chaos.Additional Notes
1. The game will check off which Body parts you have or dont have as you make your way to Mortimer in the Final Stage. More specially after entering the barred gate to his Amusement Park. Area with all the spectators cheering.
2. Each Body Part must be equipped, not just in your inventory. So be sure to hit Back button then scroll over to your relics and equip each of them. You must at least have the Relic III ability to equip them all.
3. This achievement is NOT difficulty specific so it stacks if you do it on Chaos or Total Anarchy difficulty on your first time.
4. If playing in Co-op, only one person needs to have all 5 body parts equipped to get the Good Ending in Co-op. Or your group collectively can have all 5 parts(e.g you have 2 parts and a buddy have the other 3) and it will still stack, making the Relic III ability not required.
5. If you locate some of the body parts in co-op, the glowing body part will eventually drop duplicates after a while so that all players can equip them into inventory.
6. After defeating The Angel of Chaos you will get the Good Ending and thus this achievement.
You will need to do this in order to obtain the other Story-based difficulty achievements as well.
You can select Chaos difficulty after beating the game on Normal, then Total Anarchy difficulty will be open once you finish the game on Chaos. Difficulties will be selected by entering Black portals in a special dark zone that becomes available after beating the game for the first time. There will be a long green road, just follow it and it will lead to each black portal to play on the next difficulty. This difficulty selection zone can only be accessed with a character you or the host beat the game with upon selecting them.