Well, turns out my mouse resolution is actually 800 which isn't that much... but the in-game sensitivity for Half-Life 1 is 10. That's a 10x multiplier. The default setting is 3.
@hazelnot I'd say that's a completely fine mouse DPI for that era tbh
@joepie91 Ehhh if you watch my VOD from last night it's ridiculously fast compared to any gameplay video you see online