Maybe GOG might have thought about starting a big sale already. The problem: The Outer Worlds would have had a release during that sale. And might not get the attention GOG/Obsidian Entertainment wanted. (Who knows since when the agreement exists, releasing TOW on this date on GOG. So it is just an assumption within long terms.)
Releasing a game before a sale sounds like making more sense, than releasing it during a sale. Because during large sales the rivalry between products is increased by customers buying the much cheaper games, than the new titles. (Even though TOW starts with a nice 50% discount.)
That would just be my idea why GOG has not started their Halloween/Fall Sale yet, besides starting a large sale 1 or 2 weeks before a steam sale makes a lot more sense.

Well , i'm not expecting any surprise during the next week . This sale will be an average one with the same bundles that we get every time . ( Beamdog , Larian , CDP , Ubisoft , 2K, EA and an indie bundle ) And don't forget about the usual " twitch streamer's choice , xy gameing website recomends " crap .

Some bundles offering additional discounts would be even nice (EA or Ubisoft, with their classics - ok, I agree that some diversity is needed). It's not the worst case scenario.
I'm afraid we'll just get something close to weekly sale, but with a bit longer list of titles (several hundred) and discounts exactly the same as usual. As far as I remember Halloween Sale sometimes looked like that.
If we're starting on Monday, it may be nothing more than halloween-themed Weekly Sale.

All I want is a decent discount on Terminator: Resistance.

I'd hope for a fix to GOG Galaxy before any 'major' sale.

One would assume that people purchase games with the intention of playing them. For much of Australia, this is sadly impossible within the GOG client.

Does anyone else remember the pinatas? Now imagine the same deal with Jack-o-lanterns .

Those random games for a few bucks? I've never bought any of them, but I remember them being extremely popular (hundreds of comments and a lot of people making compulsive shopping just to realize, they've already spend enough to simply purchase the exact game they wanted)...

I hope we will not see that kind of thing during the sale .

I wonder if we will receive these deals again : https://www.gog.com/forum/general/halloween_sale_blair_witch_layers_of_fear_2_call_of_cthulhu_and_300_deals_up_to_90_41594/post73

The sale is here ultimatly. But smaller than I expected.

This is just a warm-up for the Black Friday sale in 4 weeks and the Holiday sale soon after. Those are bound to be bigger.

*sigh* Of course there is no discount on Terminator. Color me surprised. -_-

You're right. One of that middle sales I never know if should be added to the list... :|

But I think it's big enough:
Halloween Sale 2020 – 850/4,5k deals – 26.10-02.11 – added to OP

I don't know if you will share my point of view, but personally I have a criterion to differentiate the sales: if the home page is modified with a special theme and colors, it deserves to be in the list, otherwise not.

Do you think that they will offer higher discounts and a wide game selection on the winter sale ?

Yes.

Historically, the winter sale and the summer sale are the largest sales of the year, and sport the best discounts (often summer a bit better than winter, but not by much).

I hope, honestly.