Speedrunning is not really a viable way to judge the game's completion time. Howlongtobeat.com rates the original Half-Life at about 10-12 hours, which seems to

Speedrunning is not really a viable way to judge the game's completion time. Howlongtobeat.com rates the original Half-Life at about 10-12 hours, which seems to gel more with my memory. My own Steam record says I logged about 10 hours on it.