Are we missing any good hack and slash games?

*cough* Diablo II ?

One can only speculate on the reason to use "` it" instead of "` em" (as in "shoot 'em up"). Creative freedom or general neglect to the victims of my blade(s)? (because they are similarly many, for they come in waves)

Grim Dawn is arbitrarily made terrible by the devs' horrible decision only to give the player a limited amount of stash space, for no good reason, which completely destroys the purpose of playing a game of this type.

Another game in this sale, Victor Vran, solves that problem by giving players unlimited stash space, which Grim Dawn devs easily could do as well. But apparently they want their game to stay bad, so therefore they don't fix that game-ruining problem.

As for Grim Dawn being the peak of the ARPG genre: I disagree with that too. Other games in this sale are much better than Grim Dawn, like Shadows: Awakening and Van Helsing: Final Cut, both of which have excellent stories, excellent voice-acting, and excellent characterization, which are three more things that Grim Dawn is terrible at in comparison.

Indeed, and probably the missing ones are the best of the best, all of which are missing from GOG, those being: Dark Souls 1, 2, and 3, and Elden Ring.

I get it, you don't like Grim Dawn. For an odd reason (which I can even find ways to agree with you), the stash. But the game play is what matters and it's way better than anything else similar. AND its story is also the best in class. As for "characterization", I assume you mean character customization? What's that matter when you're covered in gear by the end of the first zone anyway? (It doesn't.)

And... your other games? They're a completely different, unrelated, genre. Yes, they're missing. But I wouldn't ever have called them "hack and slash" games. Hack and slash implies lots of foes fought quickly. Those games are the opposite, where each and every foe in a skirmish itself.

Victor Vran I have not played, but it looks like more of an adventure game with different camera view than an ARPG.
Van Helsing is indeed amazing, but the third and "Final Cut" edition are simply not good.
First one and Second one are good. Voice acting in the first game is just incredibly done, which is why its story is considered good, I think, because its actually fairly simple.

I would not say souls series are Hack'n'Slash.
Dark Souls games can be considered Action RPGs.
Elden Ring is an action adventure game with RPG elements in my opinion.

Talking about Hack'n'Slash not on GOG:

Devil May Cry HD Collection
Devil May Cry 4
Devil May Cry 5
Metal Gear Rising: Revengeance
Samurai Warrior series
Dinasty Warrior series

...and so many more that we cannot even pronounce.
Many from Japanese developers and publishers, and as they are really agaisnt DRM-Free, they're probably not going to come here so "soon".

Have you heard about GD Stash? It's a free Grim Dawn mod. You can get it at nexusmods. It might help...

Yes. Loki, also known as Loki: Heroes of Mythology. "Good" is questionable here, but I enjoyed it for a while. No idea why it's not on GOG. I have it from a gaming magazine. It's a czech version, but all voice acting has been removed for some reason. Would re-buy it for that reason alone.

Another mention could probably go to Warhammer 40K: Inquisitor - Martyr. From the same people as the Van Helsing games, but they remain stubborn and want to keep the game always online for whatever reason. Should they ever change their mind, I'd probably get it here.

Then of course the 3rd person stuff like Bayonetta, Lolipop Chainsaw, Devil May Cry, The Lord of the Rings games from EA based on the movies, and so on.

Indeed. GDStash is pretty much mandatory, same as TQVault is for Titan Quest.

You can also just get it from ModDB or the Crate's Grim Dawn forums if you don't want a Nexus Mods account.

The mentioned Loki even had an official external infinite stash tool directly from the devs (Cyanide).