The game hasn't been on any bundles and it's very recent & expensive so I doubt they'd give it away unless its for another platform (Epic) and it would be less than 20 keys.
I doubt it would be a cheap thing to put money on. I do like the system of getting DLCs or indie games (and I hope we get some horror themed stuff), but I would rather have AW spend their resources on getting a better security to avoid bot/multi accounts.
What twinpeaksonsteam said. You can keep your fingers crossed, but I certainly wouldn't hold my breath if I were you... I don't think there's much chance The Quarry will be one of the Vault games for October.
I do hope it's going to be horror-themed tho. I definitely would like to see The Mortuary Assistant. I got this one wishlisted and will probably buy it at some point when it's on sale. After playing the demo and reading some reviews, not sure I'd pay 30$ CAD for that, it seems a tad overpriced. It's a pretty new game, but being indie, maaaaybe the dev would agree to let AWA give away some copies.
Meh. Not something I'd likely go after, unless it was on the cheaper side and nothing else caught my eye.
That said, I don't think the fact that it's a newer title automatically excludes the possibility of it being included. Shadow Warrior 3, Dolmen, Have A Nice Death, Eyes in the Dark, Hooked On You, Midnight Fight Express, and Saints Row were all new/newer releases. Granted, those are mostly smaller indie titles and B-tier games, which probably makes them easier to acquire, but they show that AWA is trying to offer some newer and potentially exciting titles in the vault. And all of them had at least 100 keys, which is still pretty pathetic, but... Some people just like to wallow in negativity.
While I honestly wouldn't expect The Quarry to show up in October's vault, feel free to hope otherwise, as it's not a completely unrealistic possibility. Just be careful of setting yourself up for massive disappointment.