No particular path

Ruins 1-1 ~ "Fallen"

• Learn to move/jump

• Meet Flowey

• Learn to dodge

• Toriel saves you

Ruins 1-2 ~ "Puzzling Beginnings"

• Learn combat with dummy and tutorial Froggit

• Switch puzzles separated with platforming sections

• Toriel leaves you

Pacifist/Neutral

Ruins 1-3 ~ "Napster"

• Rock & Color switch puzzles separated with platforming

• Napstablook mini boss

• Spider bake sale (shop)

Ruins 1-4 ~ "Butterscotch"

• Toriel introducing you to your "home"

• Short platforming section in basement

• Toriel boss fight

Snowdin 2-1 ~ "Skele Bros"

• Meet Sans and Papyrus

• Only platforming sections

Snowdin 2-2 ~ "Jape Me"

• Electric maze and XOXO puzzles

• First half of Mini Bosses (K9 unit)

Snowdin 2-3 ~ "Blue Stop Signs"

• Snowman (Optional)

• XOXO & Color Tile puzzles

• Second half of Mini Bosses (K9 unit)

Snowdin 2-4 ~ "Trousle"

• Snowdin Town (shops and hotels)

• Papyrus boss fight

• Papyrus hangout (optional level required for Pacifist)

Waterfall 3-1 ~ "Fish and Spears"

• Optional "date" with Sans (brings you back to 2-4)

• Meet MK

• First Undyne "chase"

• Waterfall leaf puzzles separated with platforming

Waterfall 3-2 ~ "Punk"

• Rain walk with MK including platforming sections

• Second Undyne "chase" with platforming sections in-between

• Fall off bridge

Waterfall 3-3 ~ "M.A.D."

• Mad Dummy boss fight

• Napstablook hangout (optional)

• Snail racing minigame (optional)

Waterfall 3-4 ~ "Heroine"

• Undyne boss fight (separated in sections with platforming in-between)

Hotland 4-1 ~ "Geek"

• Meet Alphys & Mettaton

• Gameshow

• Entry to True Lab (optional level required for Pacifist)

Hotland 4-1.5 "True Lab"

• Amalgamate fights and Platforming sections

• Find Alphys to fix elevator

Hotland 4-2 ~ "Game show"

• All of Mettaton's Hotland shows shortened into one level with platforming implemented

• Muffet boss fight

• Sans "Date" reaching MTT Hotel (Optional)

Hotland 4-3 ~ "CORE"

• Travel through the CORE with Blue/Orange lasers implemented into platforming

• Alphys date (optional level required for Pacifist. Takes you back to Waterfall 3-3)

Hotland 4-4 ~ "Showtime"

• Mettaton EX boss fight

• Find keys in Asgore's home

• Dialogue with some monsters before Judgement hall

Pacifist:

New Home ~ "Hopes and Dreams"

• Sans judges you as being good and warns you to turn back

• Fake-out Asgore fight as your friends gather

• Flowey appears and fucks everything

• Asriel Dreemur final boss fight

• Monsters reach the overworld

Neutral:

New Home ~ "Your Worst Nightmare"

• Sans judges you accordingly and warns you to turn back

• Asgore boss fight

• Flowey appears and takes control of the world using the SOULS

• Omega Flowey final boss fight

• Neutral ending phone call (changes based on your actions)

Genocide changes

Ruins 1-3 ~ "Enemy Retreating"

• Unless you switch routes, all music is gone for the rest of the game

• Napstablook doesn't fight you

• Less Monsters

Snowdin 2-1 ~ "How to pick 'em"

• Sans acts more suspicious of you

• You don't listen to Sans instructions in dialogue

Snowdin 2-2 ~ "Cold as Snow"

• Electric maze and XOXO puzzles are skipped

Snowdin 2-3 ~ "Stop"

• XOXO & Color Tile puzzles are skipped

• Less Monsters

• Sans gives you a "friendly" warning

Snowdin 2-4 ~ "Ghost Town"

• Snowdin Town is empty

Waterfall 3-1 ~ "Dirty Brother Killer"

• Sans does not appear

• Waterfall leaf puzzles are skipped

Waterfall 3-3 ~ "Glad!"

• Glad Dummy replaces Mad Dummy (will not fight you)

• Napstablook does not appear

• The snail racing business is closed down

• All doors are locked

• Less Monsters

Waterfall 3-4 ~ "But She Refused"

• Undyne the Undying boss fight

Hotland 4-1 ~ "Evacuate"

• Alphys & Mettaton are absent

• Entry to True Lab is locked

• Less Monsters

Hotland 4-2 ~ "Channel offline"

• All of Mettaton's shows are cancelled

• Sans does not appear

• No Monsters

Hotland 4-4 ~ "NEO"

• Mettaton NEO boss fight

• Dialogue with Flowey

New Home ~ "Promise"

• Sans boss fight

• Asgore and Flowey are killed

• Chara erases the world