Sources

Game:
Undertale, by Toby Fox and Temmie Chang

Songs (in order of appearance):
Problem - Ariana Grande feat. Iggy Azalea
Rude - MAGIC
Soldiers of Love - Lighthouse X
Call Me Maybe - Carly Rae Jepsen
Best Song Ever - One Direction
Sexy Back - Justin Timberlake
Mother Knows Best - Tangled
I'm A Joker - Anri Jokhadze
Popular - Eric Saade
All I Want for Christmas is You - Mariah Carey
Why Can't We Be Friends? - War
A Thousand Miles - Vanessa Carlton
Fancy - Iggy Azalea
Too Sexy - Right Said Fred
Ridin' Dirty - Chamillionaire feat. Krayzie Bone
I Am the Bread of Life - Suzanne Toolan
Something in the Water - Carrie Underwood
Who Let the Dogs Out? - Baha Men
Umbrella - Rihanna
Paparazzi - Lady Gaga
Bad Boy - Mallory Everton, Whitney Call, Natalie Madsen
1944 - Jamala
Lighthouse - Nina Kraljić
I Wish I Could Go Back to College - Avenue Q
Glowing in the Dark - The Girl and the Dreamcatcher
Halo - Beyoncé
Dangerous Woman - Ariana Grande
Walk on Water - Ira Losco
Facebook Uh Oh Oh - Valentina Monetta
Cool Me Down - Margaret
Beautiful Pacific Islands - Vanessa Quai
Cake to Bake - Aarzemnieki
Heroes - Måns Zelmerlöw
I'm the Bomb - Pigeon John
Me and my Broken Heart - Rixton
Don'cha - The Pussycat Dolls
My Heart is Yours - Didrik Solli-Tangen
Heathens - Twenty One Pilots
Miracle - Samra
Kiss the Girl - The Little Mermaid
Hold Me - Farid Mammadov