GOG is also having a Halloween sale
https://www.pcgamer.com/gog-is-also-having-a-halloween-sale/
Steam is the big boy of digital storefront seasonal sales, but it's not the only game in town. GOG is getting in on the Halloween action with its Trick or Treat Sale, which is maybe a little less thematically stratified than Steam's Halloween Sale, but still well worth picking through.
Not sure where to start? As always, I am here with a few suggestions: