I like playing games like this..... but I always get my butt handed to me...... but I like playing games like this......

Trailers are looking good. I'll wait for few gameplay reviews, but it might be my entertainment for the coming weekend.

I know how you feel.
I like shmups. I am absolutely terrible at them, but I like them.
Oh, and, I like this type of games too.

Rated M on PS5, yet you listed it as 18+.

The ESRB rating is M (= 17+).
The German USK and the European PEGI systems don't have a 17 rating. But they do have 16 and 18 ratings.
Therefore, GOG, as an European company, goes with the higher rating - the 18 rating.

It's PEGI 16.

Apparently, from the few reviews I saw it seems to have nice combat, be solid and polished from a technical standpoint , but it's pretty short (~8 hours) and could have used more variety in levels and enemy design. Still it seems rather positive overall.

8h gameplay for soulslike game for 22 EUR? If true, that's rather big minus in my book :(

It's also USK 16.
But the highest rating is the ESRB's "M" (= 17+).
And as we have already established: neither PEGI nor USK have a 17 rating.
Therefore GOG (again: as a Europeasn company) goes with the next higher rating after that: 18.
That way, they don't get in legal troubles.
What do you care anyway?
Is it age restricted for you in the US? Are you banned from buying it? I don't think so...so, where's your problem?

omfg again

GOG uses 17+ age gates often, I don't see why one couldn't be used here.
It's not nearly as big a problem here as with Shinovi Versus since this can't be easily mistaken for an eroge, but GOG is still mislabeling it.

Is not "grueling" a negative description? I am not sure I want to play anything described as grueling, seems like the oposite of fun

If they don't want legal troubles they shouldn't have eroges without age gating.