Straight from the site:
What can I request a refund for? Valve will, upon request via help.steampowered.com, issue a refund for any title that is requested within 14 days of purchase and has been played for less than 2 hours (this includes online, offline and shared library playtime). Even if you fall outside of the refund rules we’ve described, you can submit a request and we’ll take a look at it.
Looks pretty clear to me, you had plenty time to refund it.
I mean, I don’t want to need an active Internet connection to play a single player game.
Being forced to become dependent on a external party for a single player game is stupid and dishonest. What happens if their verification servers goes down?
At least, I assume that it needs an active Internet connection to check if your logged in or not.
Thought for a moment that it was the onion.