1) I'm always skeptical of claims of free games. Reading the text of the tweet doesn't mention ANY free games. I hope people aren't setting themselves up for anger or disappointment if gog doesn't give out free games.
2) This interpretation is supported by gog saying the most wishlisted games will be super cheap. You don't offer discounts on games you're giving free. So it sounds like a sale on certain games. At least this sale is likely to include games that many will want, instead of three dollar mystery boxes.
3) The "granting thousands of wishes" made me think that they were going to fulfill something from the community wishlist... something with thousands of votes. Nice, but not thousands of free games. Think Grim Fandango finally coming here, or NOLF, or something like that (yes, I know GF is here).
Consider this wish, which is pending: https://www.gog.com/wishlist/site/use_time_travel_to_add_games_that_havent_been_released_yet
4) My email only mentions games on sale, no freebies or wishes. It seems odd marketing for gog to announce the gift of free games only on twitter and not even on the forum. Wouldn't the forum be the BEST place to announce a reward for forum regulars?
5) I strongly second TARFU's point about entitlement and gratitude. Gog doesn't owe us anything, nobody owes us free games, we are not entitled to anything. Be grateful for what you are given, even if you don't plan on keeping it or using it. Smile and say thank you.