This is “Silhouette” from “LaTale”, a 2D side-scrolling online game developed by Actoz Soft.
The music was composed by D.Z. (team name? I don’t know the details)
This is a long-lived MMORPG that was launched in 2006 and is still running.
All the BGMs for this game can be downloaded from the official website.(This is No.266)
I liked the mysterious but elegant atmosphere of the song, so I made a TAB score.
Overall, it’s made diatonically.
Personally, I like the melody in the 6th bar.
The movement from the M2nd to the m3rd, which is from nonchord tone to chord tone, resolving in half notes is nice.
The 11th bar is a picardy third that resolves to an I in parallel key.
The effect is as if a light has come on, or a vision has opened up.
This also functions as the V of D minor, the next modulation.
The sound of c#, a note of the D harmonic minor scale, provides a natural modulation.
There is a b♮ in bar 18th, which seems to be a temporary ii of D major.
Perhaps because there is a moment of brightness mixed in with the darkness, it gives an mysterious impression.