As discussed in this thread, there isn't an official limit for the refund policy. However, refunds are monitored for signs of abuse, which is why OP wasn't offered a cash refund (even though he just left the game running without playing it).

If you don't use Galaxy:
- as soon as you download the game, you waive any statutory rights for a refund
- as soon as you download the game, you are not entitled to a refund under the extended 30 day right of withdrawal policy
- downloaded games may be eligible for a refund under the 30 day refund policy, which is at the discretion of GoG and monitored to minimise the chance that users aren't abusing the system.

So, unless you're exhibiting a pattern of behaviour that makes it look like you're gaming the system, they are likely to offer you either a refund to the original payment method or to store credit.

Hehe, that's pretty funny. I guess there might be some games where there's a passive benefit to runtime, e.g. idle games like Cookie Clicker.

I remember jumping everywhere in Morrowind and Oblivion to max out one of the stats. Although you could also argue that in doing this, you're technically playing the game as you're progressing (just doing it in a very lazy way!)