Caveman Ending

The Caveman Ending is a secret ending in YIIK: A Post-Modern RPG. On July 2nd, 2019, a team of people discovered the ending through illegitimate means.

The original post describing the instructions to achieve this ending are as follows.

step 1: create a character called Shag Hyde
step 2: skip the golden alpaca boss fight
step 3: go to the wetlands and defeat the puppet mistress to obtain the item [Sheriff's Hat]
step 4: persuade rory into killing himself
step 5:defeat meteor alex in combat or lower his health to 1 and then use the Sheriff's hat, then give up to obtain [Sheriff's badge] alex will be teleported to a secret location known as the north pole
step 6: move to the right for 10 minutes straight to find a caveman frozen in an ice cube, trade him the sheriff's hat and badge to unlock the secret ending where the caveman is frozen in the ice cube while Alex and panda are out there in the north pole wondering where is the caveman.

These instructions are not 100%, and are a bit vague in some areas, causing some people to believe the ending did not exist. While at first it was speculated this was the game's hidden 3rd Ending, none of the hints given about the ending correlated to the Caveman Ending in any way, causing many heated debates in the fanbase.

The ending was strangely removed in version 1.07, but some players say you can still access it with glitches in the PS4 version.

Refined Walkthrough

While NG+ is not strictly a requirement, it's essentially needed since you need to be at least level 40 for one of the unique items found in the route. (It's a common misconception that NG+ will lock you out of the route. This is not true.)

1. When the game asks you to name yourself, you must be named "Shag Hyde"
2. Skipping the Golden Alpaca fight isn't as easy as it sounds, and you need the correct item in order to run away. In Frankton, there is a sound cue which sounds a bit like a worm hole opening. If you open a trash can during that sound cue, and you are at least level 40, any item that would've been in there would be replaced with a Lemonade Horn. Keep in mind they are only available for grabs during the section where Michael and Alex are training to meet up with Vella again. Using this item in the battle with the Golden Alpaca will allow you to properly play the running away minigame, but remember- you're using an item. If you run out of Lemonade Horns, you have to restart your playthrough. The rest of the dungeon will play out like normal.
3. The next time night falls, meet up with Chad. He will tell you "It's not wise to go alone." Panda will be upgraded to party member status now, which is very helpful for the upcoming fight.
4. Next, enter KNN and grab the Red Disk. Head to the Reservoir and the area will be transformed. (This is the "Wetlands" as mentioned in the original walkthrough.) You'll be able to find the Puppet Mistress quite easily, and they're a pretty tough fight. Level 40 is a good enough level to defeat them. Use Panda Barrier to block the string manipulation attacks, they're easily telegraphed by the blue glow behind them. Defeating them will gain you the Sheriff's Hat.
5. In Chapter 4, do not pick up Rory. This should be enough to trigger their death. You can then head to the Wind Town Water Tower to fight Proto Rory. They do nothing but defend so just use your most powerful attacks and move on.
6. In the fight against the Proto-Comet, lowering their health to about 20% and using the Sheriff's Hat will teleport you to the North Pole. Move right for a while and the ending will play out.

Trivia

• It's believed the ending is based off of a Scooby Doo meme.
• The Puppet Mistress uses an attack based off of Michael's unused Soul Capture move.