I write to music, occasionally video game music, so I have almost too many answers to this thread. I’ll pick a couple of favorite and then list a bunch of others at the bottom.
Pokemon GSC - Dark Cave / Idk what it is, but something about this track — which is supposed to be kind of terrifying I think, since it accompanies a cave filled with nothing but inky blackness and Zubat (well and Dunsparce) — but it just puts me in this state of total concentration. Maybe it’s so successful at being suffocating it tricks my brain into hyperfocusing on one task. Wrote most of my undergrad thesis to this one, along with the regular Johto trainer battle music.
Into the Breach - Old War Machines / There’s something incredibly soothing about this track, and it does the same general thing to my emotional state as a warm bath or a nice blanket.
That Old Train Ride (Half-Life 2 remix) / This one might be cheating as it’s a remix of a bunch of tracks from the HL2 soundtrack, but it’s just such a peaceful, mournful, beautiful track.
Others: Haltija (Forza Horizon 4), Golden Ridge Golden Feather Mix (Celeste), City of Tears (Hollow Knight), Drenched Bluff, Brine Cave, and Temporal Tower (PMD: Explorers) (honestly, basically every song from PMD would fit here), Entei’s Rampage (Pokemon Ranger).
Oh… and I almost forgot the best of them all. Majula. No other words necessary.