Plus they subvert it pretty awesomely in the third.
basically you save an elf girl and she goes "what, expecting a tumble out of gratitude? Get your head out of your ass"
Actually, pretty much the only people you Can 'do' in the third is just people who already know you. Or seductress lady-thieves.
I mean, I'll admit he's a powerful main character- but I would say only having the ability to save and load makes him a Mary Sue.
Or I have the definition wrong. For me, if things go badly for a character, and they curse and sweat- that's an instant sue-disqualification.
Well women were almost outright jumping at Geralts crotch in the first game (I think you could have sex like... 3 times in the first act alone.) but it was partially understandable because geralt is pretty much a completely safe person to have sex with.
Infertile so he won't leave you pregnant.
Immunity that kills any would be STD so he won't pass any STDs.
Manly and physically fit. (Altho admittedly he is described as having an "Ugly Mug" in the book).
Personally i think it was a good idea that CDPR backed away from all the sex in W2 and 3 because if you think about it W1 had more contrived sex than Ride to Hell and that's not really representative of real (non amnesiac) Geralt and his values now is it?
As for Mary Sues...
A maru sue needs to have a solution for everything at hand.
Locked door? I'll open it with a hairpin despite never doing that before!
Guard in front of the door? I'll woo him with my charm!
We're both the same gender? No problem i'm so sexy i'll make him gay or i'll use my secret shaolin punch technique and knock him out through the door!
He's too far away?
Well i'm also an empath and will influence his mind and tell him to help me escape!
That is a Mary Sue.
Geralt on the other hand is described by having a set of skills and atributes.
Can do simple gesture based magic.
Is great with swords.
Was genetically enhanced granting him above average agility, strength and dexterity along with being mostly immune to toxins.
Due to the toxin resistance he can use witcher only potions and elixers (with those things being so toxic even witchers can just barely withstand their negative effects).
Knows just about everything about monsters.
Is an optimist turned pessimist that would love to become an optimist again.
And that's it. That's his entire toolkit and most of his character described.
If anyone it would be Ciri deserving the Mary Sue Title... but that's another story and my post would be even more tl:dr