Technically not a Halloween sale but I recommend picking up freedom fighters from the publisher sale if you havent played it yet. Fun shooter with some unique twists. Used to be an Xbox cult classic.

https://store.steampowered.com/app/1347780/Freedom_Fighters/

the macro gameplay loop more than just getting better at the game so you can survive longer?

No, but the worse you do within a run the harder it gets later on. Things tend to spiral out of control on Project Zomboid and if you go in blind you will have some pleasant surprises that will definitely make you do 200 iq plays to solve it.

Exploration is a big part of the late game and it gets insanely difficult at some points. I do recommend boosting XP if you play alone (I put it to 2x) so you dont spend hours sitting in a house reading books to get mauled by a random zombie that was looking for a snack.

Im easily bored with games and I got a solid 200 hours before I dropped it.