Hyperlight Drifter

Cobalt Core

They're in the same vein but it's some of the best chiptune-esque music I've ever heard. They're not these one note, one tempo, same vibe over and over again tracks. They have feeling and movement. Almost melancholic at times. Scary in the case of HLD. They remind me a lot of mid 2010s prog metal in some respects. Not the heaviness or the distorted guitars, but the melodies and creativity with sound that pushed music forward in those years. Like the last track of the Cobalt Core ost flows right into My Last Serenade by Killswitch Engage and it's a chefs kiss of greatness. They're both top 5 video game ost for me.

All the Astro Bot games have phenomenal soundtracks, Kenneth CM Young (of MediaMolecule) is brilliant and knows how to write really catchy earworms. Really got stuck listening to Trapped in Time and Papa Tree.

Literally every Supergiant game.

Metal: Hellsinger https://www.youtube.com/watch?v=HidvYgF9-8Q&list=PLJQHL1SwXgq0m1LuxDGHDEWnBDFdYc2Vk&index=9

Planescape Torment and Icewind Dale. Not all the tracks but many of their tracks are great. I play them on the loop.

Also The Witcher has great soundtracks, I often play them on the loop while I was working.

Hi-Fi Rush

Lollipop Chainsaw

Kingdom Hearts

Guitar Hero 3

Tetris Effect for me.

For me, it's Xenosaga episode 1 on the PS2. It's performed entirely by the London Philharmonic Orchestra and it's my favorite OST of all times

Rebel Galaxy - country rock genre? Very unique and different sort of music.

Trine 1 & 2 + Transport Fever 1 - instrumental background music good for concentration, working, studying or just relaxing.

I'm surprised no one said Touhou yet.

https://www.youtube.com/watch?v=XqH79HDfrr8

Also, I see a lot of love for Celeste and Jet Set Radio in the comments. Y'all have good taste.

Not For Broadcast

Gonna list 2 that deserve the "great soundtrack" tag on steam:

• Assault Android Cactus - twin stick shooter/bullet hell with cute android girls blasting robots. Techno stuff, with my 2 favorite tracks being Liquorice (it's divided in 3 "acts" as it's a boss music) and Assault
• Cloudbuilt - 3D platformer with focus on speed. I suck at this game, but the tracks are amazing, with my fave being Aurora

Someone else mentioned Unreal 1, but I gotta say, Unreal Tournament 2004 has some absolute bangers, like Morpheus3, Hyperblast Redux, Level11 and Convoy

I'm surprised at the lack of love for 13 Sentinels - Aegis Rim here. It's a little more on the electronic side but fans of the NieR soundtracks in particular would vibe hard with 13S-AR. A couple of standouts - Lysine and Brat Overflow

Bunch of bangers on this list already, but the one that sends shivers up my spine to this day is Crusader Kings 2.

Citizen Sleeper

I just finished Frostpunk recently and have to say I really enjoyed the soundtrack.

One that sicks in my memory years after playing it is the soundtrack for Expeditions: Conquistador.

Runescape.

Right from the login screen its always been iconic