This is “Chapter Complete” from 2D platform game “Celeste”, by Extremely OK Games.
It’s a short jingle that plays every time you clear a stage, but I like it so I copied it.
The chord progression is V9 – ii6 – I9, it ends gently by going from subdominant to tonic.
V9 is V7(9,11) if you consider the melody as part of the chord tone, so it has a complex sound like the ones used in jazz.
Also, in ii6, the melody and chord tones are clashing at the semitones, creating tension and reinforcing the sense of relief when we reach I9.
The reason I have two pieces of sheet music is that I have also prepared one in standard tuning for those who have trouble with double drop D tuning.
The standard tuning requires an extension of the left finger, but I think it is relatively easy to play.
The difference is the addition of a perfect 5th degree note. I wanted to add a perfect fifth to the chord to give it the bass “thickness” that the original has, but five left fingers would not be enough… After a bit of trial and error, I ended up with a double drop D tuning.
Guitar playing tips
If you can stroke, you can mute the strings you don’t play with your left finger.
I’m not good at stroking, so I use my thumb to play the 5th and 6th strings at the same time.