Hi, welcome. I noticed that all the tickletale stories aren't finished which is a shame. So I'm deciding to make this! This is every change that is made:
Frisk is female in this, I'm saying this just for clarity sake.
Everyone in the underground loves tickling (obviously)
The 6 humans are alive! Their names, genders and where they live are as followed:
Integrity - female - Amelia - lives with toriel and Lucy in the ruins
Kindness - female - Lucy - Lives with Toriel and Amelia in the ruins
Bravery - male - Lucas - lives with sans and papyrus in Snowdin
Patience - female - Chloe - lives with Undyne in waterfall
Perseverence - male - Mason - lives with Alphys and Mettaton in the lab
Justice - Male - Asher - lives with Asgore in New home/throne room
Monsters don't wish to kill any humans. instead, they don't even wish to go to the surface, they just want to live peacefully underground (aside from one certain flower)
There isn't a royal guard as there is no need for one. So Undyne is just a very strong monster and Papyrus doesn't have any aspiration aside from making friends.
All magic attacks done by monsters now will just tickle the person rather than do any damage to them
For a death to happen, someone will have to be tickled until they run out of breath. This is the only way a genocide route is possible.
And that just about covers all the main changes. Hope you enjoy this adventure frisk will have to go on with plenty of laughter to accompany it.