It's... not a gay game. At all. It's a game with exclusively male NPCs and a gender selectable PC. That's the point of it. The description is very explicit about that.
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All of the romanceable/bangable options just so happened to be a bunch of dudes, several characters are canonically bi/pan ((Arthur and Rylan for example)) regardless of the gender of the player character. The Creator themselves happens to be LGBTQI+ ((A gay man, if I recall correctly))
I don't know what you would call that, but I certainly wouldn't call it straight.
It's not "just so happened." That was fully intentional.
I certainly wouldn't call it either straight or gay. i might call it bi/pan as you yourself already did, or just LGBT+.
You appear to be acting as though I don't have a comprehension of LGBT+ identities. I am an AMAB nonbinary androsexual person. It is because I understand LGBT+ identities that it is very clear to me that this isn't at all anything I would call gay.