While it features the same cast as Undertale, the characters are shifted so they fill different roles and stories, without changing personality nor species. Storyshift explores the effects of placing characters in different roles--how they act, and the consequences of their actions on themselves and the world around them.
The original Storyshift comic ran from December 2015-2016, until it was put on indefinite hiatus in April 2017.  In July of the same year, it was announced that Storyshift would be rebooted and return in comic format.  That December, the first part of the reboot comic was released, though several days later the rest of the comic was officially cancelled. However, it was stated that the reboot would continue in written format. 
Long long ago, two races ruled Earth: MONSTERS and HUMANS. One day, war broke out between the two. After a long tiring battle, the humans won. Their sorcerers sealed the monsters UNDERGROUND with a magic spell.
Many years later, in XXXX, legends say that those who fell down Mount Ebott would never return. A human child climbs the mountain for unknown reasons, and ends up falling down an enormous hole.
The present story begins with Frisk waking up in the Underground and meeting Boogie, who holds them hostage after they try to flee a tutorial battle. Prince Papyrus comes to the rescue, and escorts Frisk through Old Home while teaching them how to solve puzzles and peacefully resolve conflicts. He eventually allows Frisk to continue on their own, as they find their own path throughout the old ruins.
- Boogie takes the role of Flowey
- Papyrus takes the role of Toriel
- Papyrus is the prince of the Underground
- Alphys takes the role of Napstablook
- Alphys is a sympathizer for the rebels
- Chara takes the role of Sans
- Asriel takes the role of Papyrus
- Toriel takes the role of Undyne
- Asgore takes the role of Alphys
- Undyne takes the role of Mettaton
- Sans takes the role of Asgore
- Sans is the king of the Underground
- Napstablook takes the role of Asriel
- Mettacrit takes the role of Chara
- Mettacrit is the narrator for Frisk
- Old Home replaces the Ruins
- Frosted Fields replaces Snowdin
- Wetland replaces Waterfall
- The Furnace replaces Hotland
- Dreemurr Labs replaces the True Lab
- The Mountain's Soul replaces the CORE
- New Hope replaces New Home
- Frisk will now be wearing their armor in their overworld sprite. 
- Undyne is no longer a cyborg, just a fish monster. 
- Each area is divided into differently-colored sections in order to signify progression and give the scenery some variation. They are also split into two paths, with a warrior's path and a puzzler's path. An example of this showcased in the write up is Old Home.
- Locations have been given brand new names and designs instead of reusing Undertale's.
- While some plot points from preboot will still be relevant, a good chunk of it has either changed or been given a drastically different context for the reboot. 
- There has been a major overhaul with the overall tone of the Underground. Things worked differently under another ruler, and monsterkind reacted to it over the years. 
- The reboot will focus significantly more on the impact of characters' actions on the world around them, as they are in entirely different roles than their Undertale counterparts. This aims to solve an issue with the preboot, where the main story itself was relatively unchanged.
- Storyshift has never featured personality swaps, as Voltra "detests them with a passion." While characters are certain to act differently based on the circumstances given to them, they will never act like the character whose role they are put into. 
- Indefinite Hiatus - Storyshift Reddit
- The AU is NOT cancelled - Storyshift Reddit
- The reboot comic is canceled, however... - Storyshift Reddit
- First and foremost, Frisk will be wearing their armor in their overworld sprite. - Storyshift Reboot Write Up Introduction
- Is Undyne a robot like Mettaton? Is she still a cyborg like in the preboot? - Storyshift Tumblr FAQ
- Will any of the preboot plot points still apply here? - Storyshift Tumblr FAQ
- Without spoiling it, how much can we expect to change in the reboot? - Storyshift Tumblr FAQ
- Are there personality swaps? - Storyshift Tumblr FAQ