How many hours does it take to complete Firewatch?

Excuse me, could you please clarify for me the amount of time it takes to complete the game "Firewatch"? I'm considering purchasing it, but I'm unsure if I have enough free hours to fully enjoy the experience. Would you say it's a short, quick play-through, or does it require a more substantial investment of time? I'm hoping for a rough estimate of hours to expect, if possible. Thank you in advance for your help!