Xbox:
Oddworld Stranger's Wrath, Ninja Gaiden Black, Shenmue 2.

X360:
Bioshock, Tales of Vesperia, Halo 3.

Xbox One (didn't own):
Sekiro, NieR Automata, Signalis.

Series X/S (didn't own):
I just realized that I (probably) didn't play an original gen 9 game that is available on Series X/S. I guess Resident Evil 8 but I only played that for an hour or so in VR.

This generation seems fantastic as far as quality games, but I've been prioritizing playing older and cheaper games. Will eventually get around to playing more of the newer stuff.

Xbox
>Half Life 2
>Knights of the Old Republic II: Sith Lords
>Juiced

Xbox 360
>Mass Effect
>Dishonored
>Metro 2033

Xbox One
>Sunset Overdrive
>Forza Horizon 4
>INSIDE

Xbox Series
>Cyberpunk 2077
>Forza Horizon 5
>Elden Ring

Xbox

1. Halo: Combat Evolved

2. Halo 2

3. Panzer Dragoon Orta

360

1. Bioshock

2. Bayonetta

3. Bioshock Infinite

Haven't explored enough of the Xbone or Series library yet.