Steam will stop issuing refunds if you play two hours of a game before launch day

REFUNDS ON TITLES PURCHASED PRIOR TO RELEASE DATE

When you purchase a title on Steam prior to the release date, the two-hour playtime limit for refunds will apply (except for beta testing), but the 14-day period for refunds will not start until the release date. For example, if you purchase a game that is in Early Access or Advanced Access, any playtime will count against the two-hour refund limit. If you pre-purchase a title which is not playable prior to the release date, you can request a refund at any time prior to release of that title, and the standard 14-day/two-hour refund period will apply starting on the game’s release date.