If you somehow managed to avoid buying Angry Birds Seasons over the past 20 months, your patience has paid off.
Apple's "week" began yesterday (Thursday), so you've got roughly six days to take advantage of this offer.
True to its name, Angry Birds Seasons is a theme-oriented spin-off of the original game -- that theme being, well, seasons. Thus you've got level collections ranging from summer and winter to St. Patrick's Day and Halloween.
Rovio updates Seasons on a regular basis, with the game now approaching a whopping 300 levels. All the new themes and levels come free, making for almost unparalleled bang for the buck.
In this case, bang for the click, as no money will change hands unless you make an in-game purchase. (The 99-cent Mighty Eagle, for example, can help you get past a particularly tricky level.)
It's worth noting that these are the full, ad-free versions of Angry Birds Seasons. If you don't yet own the game and want to see what all the fuss is about, this is the freebie for you.