If you like point-and-click adventure games, there are a bunch in spooky territory:
Maniac Mansion/Day of the Tentacle
There are more, but these are the ones I’d start with if you haven’t played them.
Not sure whether you could consider it a Halloween game or not, but Gears of War. What’s more Halloween than an apocalypse?
I played a bit of Hellblade: Senua’s Sacrifice last night for Halloween, and it definitely has that spooky Halloween vibe. Definitely check it out if you get a chance.
I’m not going to say it’s my favorite Halloween game (that goes to either Grim Fandango or Costume Quest), but it has been a worthwhile experience so far.
MediEvil. It’s not a horror game, but I always think of it as the game that carries the Halloween feeling the best.
Costume Quest
Came here to say this.
I like me some horror games around Halloween, but this is by far my favorite actual Halloween game.
I don’t like horror games but Viscera Cleanup Detail I can accapt.
The only horror elements are the aftermath of a big and bloody gun fight and you’re tasked to clean up the mess. ;p
Of course, The 7th Guest! And The 11th Hour! I’m actually a bit obsessed…
7th guest VR is fantasic!
It’s not old, but I saw someone post their playthrough of Pumpkin Jack, which you play as a jack-o-lantern in a spooky-themed game.
I haven’t played it myself, but I’m a fan of fun platformers so I may check it out.
I don’t know about Halloween as such, but ghost-themed, I guess Ghost Master. Twenty years old now, but try to make use of various ghosts with different abilities to drive people out of various buildings and houses.
