Play as Kris. The character creator is replaced by Kris, with sweater and hat choices. In the Dark World you become Dark World Kris.
Susie lives on the farm. She follows you around, helps with chores, talks, and has her own opinions about what the villagers say.
The closet in your farmhouse drops you into Castle Town, Deltarune's Hometown Dark World, with Lancer, Tenna and a Deltarune item shop.
Make a Dark Fountain. Buy a Kitchen Knife at Pierre's and use it indoors: Kris carves the fountain, light and beams fill the room, and the house becomes a giant Dark World built from its own objects.
Darkners. The house's objects come alive. Some are friendly and chat. Others chase you, so dodge them or fight. Clear a zone by sparing or defeating its Darkner. Seam runs a shop by the fountain, and Chillby the fridge is always around.
Deltarune battles. Kris, Susie and Ralsei fight with the real battle screen: FIGHT bars, ACT, MAGIC (Rude Buster, Heal Prayer, Pacify), ITEM, SPARE, DEFEND, TP from grazing, and the SOUL in the bullet box.
Chapter doors. Five doors in the Dark World's start room start your real Deltarune at Chapters 1-5.
Needs Deltarune (Steam) installed. Every sprite, room, sound, song and line of Deltarune text is read from your own copy at runtime. No Deltarune files are included.
Credits: Deltarune by Toby Fox. Bundles SMAPI 4.5.2 by Pathoschild (LGPL-3.0, unmodified, source at github.com/Pathoschild/SMAPI) and SharpZipLib (MIT).