What if you can play and finish a game that can be beat in less than 2 hours? There are some of them like indies such as Gone Home?
Lol? An over sight? Not sure if this has been asked yet.
Not really an oversight, since there are plenty of games around that last less than that. They can track the frequency and rate you ask for refunds and the games you are doing them for. If they determine you are abusing the system for "free trials" they can blacklist you.
Abuse
Refunds are designed to remove the risk from purchasing titles on Steamnot as a way to get free games. If it appears to us that you are abusing refunds, we may stop offering them to you. We do not consider it abuse to request a refund on a title that was purchased just before a sale and then immediately rebuying that title for the sale price.