(Disclosure: I work at GS)
I'm looking forward to this. I'm part Irish (and Black, I'm Mocha Cream!) so the Celtic inspiration is really interesting to me. I really like the narrator and the whole game just looks charming to me. Sadly, try as I might, a lot of my customers don't share my interest. Though, of the few preorders I do have, they are all women or buying for their daughters. Which it a great thing.
As for why GS is getting into publishing? I can only guess but lets take a look.
1) It diversifies their company. GS is dipping their toes into a ton of things. 2-3 years ago is was collectables. Now it's worth over $100 million to them. It's like we have a Funko Queen Ant in our back rooms spitting out POPs. =P However, it's also meant some awesome statues come through I can offer too.
2) Mechandising rights. A couple of people commented on this but its true. Game devs keep the IP but GS probably keeps the merch rights. So, more exclusive merch with nice margins on them. If Song of the Deep is a success and reviews wrong, maybe those Merrin POPs will sell more. The T Shirts (which was cool btw) will sell more. Etc. Also, the potential to expand the IP for the future.
3) Retail is on the downslope. It's a fact. Go look it up. Retail as a whole is down and has been trending down over the years while travel and leisure trends up. People aren't buying as much as of late. So, GS being a retail company, is trying hard to stay ahead of the curve and offer more. Look at their messaging. You'll see "value" and key words like that. So, offering these games exclusively to them is part of that. Especially at $15. That's an easy add on. So much more so if the game is good. Which I think something like Song of the Deep is (given demo impressions).
On a personal level, if Song of the Deep is good and I play it and believe in it. It will be awesome for me because I can suggest it to everyone. It's only $15 for a potentially good Metrodvania. A story of a little girl, putting together her own submarine to face the deeps of the sea to find her dad? Isn't stuff like that something we have been asking more of? As a gamer, that's something I can get behind. As a Store Manager, I can even more so because I can suggest the game and believe in it. Not as something I'm told to do (and if the game is not good, I won't be doing this).
So, I have high hopes for the game. I have the CE on order even though I'll probably get a free copy.
Sorry for the rant. I'm a veteran Store Manager who has gone through some shit (liver transplant couple years back), has become a bit of a minimalist and simply looks for games I can believe in that people will enjoy instead of pushing them because I'm told to. It makes the job much easier and more fun.
(More disclosure: There is a profit sharing model for this game in the company (which is cool!). But it's so tiny that I don't give a shit.)