I haven't played to Undertale, Hollow Knight and Cuphead, but it's in my project.
The music of Danny Baranowsky and Austin Wintory were a real revelation for me.
I mostly enjoy simulation/strategy/management games like civilisation, Banner Saga, Oxygen not included, Frostpunk, Reus, Total war, Game dev tycoon and Endless space ; and adventure/RPG games like Transistor, Kotor, The witcher, Kingdom come deliverance and Mass effect . But I also really liked other kind of games like Bastion, Fez, Fract OSC, Machinarium and Them's fightin' herds.
I have a lot idea for sim/tycoon/rpg/strategy games that I want to develop. For the composition I want to try every kind of universe.
For now I'm learning Game Maker, and I also work on an indie game with two friends for the music.
Did you studied coding ?