Throughout the entire time period Spock has spent living among humans, not a single one of them has ever questioned his affinity towards the Terran board game named 'chess'.
It was generally accepted among logical beings that explaining the lack of a phenomena was more challenging than explaining its presence. It presupposed one developed a complex system of expectations of ones' surrounding and, in addition to that, had a sufficient understanding of these expectations to reevaluate them as required. Spock fulfilled both criteria, and therefore had no reason not to try.
This particular pattern directly conflated with at least two hundred and four interactions led with forty-nine different humans, which have proven time and time again that members of this species (or, to be exact, individuals affiliated with Starfleet) expected him to behave in accordance to their popular image of a Vulcan. They raised eyebrows when they found out he knew more about their history than they did, acted surprised when he ate food they considered excessively human (as if other options were overabundant), offered him a hand to shake and then retracted it in incoherent babble about how they didn't mean to be vulgar and is it true what they say about Vulcan hands?
And yet, the humans around him reacted no more to seeing him play chess than they would if they saw him walking down the hall.
His very first hypothesis on the matter was that the game simply wasn't widespread, and the humans in question didn't recognize it as their own. It was, after all, his mother who taught it to him; as he spent more and more time among humans, he came to realize that she was not only more compassionate than others of her species, but also more intelligent. This notion did not seem implausible.
It was Nyota who disillusioned him of it eventually. In the course of an otherwise unremarkable conversation one evening, she asked him whether or not he was allowed to play as a child. He told her how his father disapproved of his wife's insistence that children needed playtime to develop properly, and how she eventually found a game he did not find completely reprehensible.
She told him she knew how to play, if only in the barest sense of the word, "But then, who doesn't? Most people could tell you how the pieces move, but couldn't play to save their lives."
"I can envision no situation in which lives would depend on winning an abstract strategy game."
She smiled a little and paused to consider the matter. "Breaking news: Disgraced chess prodigy straps winner to explosive device. Public rematch follows," she proposed in a tone strongly reminiscent of a Terran reporter. He was not entirely certain how he was meant to react. For one thing, the scenario at hand was completely implausible, and anyway, her wording was consistent with that of writtennews.
"This is highly illogical. Though I do not possess sufficient data to formulate a statistic, I assure you that-"
Still smiling, she moved from the other chair into his lap and pressed a single finger to his lips. That put an end to the argument.
Mere days later, it turned out that Nyota fell under her own definition of people who 'couldn't play to save their lives'. He made a brief effort to teach her, but she had trouble grasping simple ten-turn strategies and did not seem nearly as enthusiastic about it as she was about school work and old Vulcan literature and almost anything else. Finally, she informed him in an uncharacteristically unrefined sentence that it was "lousy" of him to enjoy "crushing" her "all the damn time" and that "for God's sake, you're supposed to learn these things as a child or not at all". Before he could inform her that Vulcans did not 'enjoy', she slid back into her normal speech pattern. "It has been proven that strategy games improve cognitive thinking... most of all, in children. And well, in people of advanced age. I'm not either of the two, am I?"
"No, Nyota, you are not."
"And neither are you. I really don't think your cognitive thinking needs improvement, either - no, don't give me that speech. I know there's no such thing as being smart enough-" And oh, how she knew, with her endless gathering of new languages and dialects that would drive most humans into sensory overload. "-but you're at a point where you know how to learn and just need to do the actual learning. It's not like anyone here in the academy could give you a run for your money, anyway."
He did not argue, nor did he remark that he did not play chess for money. He recalled reading about this particular figure of speech approximately six point three days ago.
"...So really, you have no practical reason to do it. You know, unless you're enjoying yourself." She smirked somewhat guilefully.
Soon after that - soon, and closer to the Narada incident and everything it entailed, though of course, they couldn't have known it at the time - he finally gave up on trying to find a decent chess partner within his current establishment. It was ironic that he, the least human of them, would become better than any of the humans at the game they themselves invented.
He could, of course, find a certain logic in it if he took the human point of view into consideration. As Nyota described it, they considered chess to be an intellectual game, one that anyone could learn but only the elite could master. If there was one aspect of their culture he could be expected to perform greatly at, then this was it. He knew this was why his mother taught it to him in the first place; it was unmistakably human, rooted firmly in earth's distant monarchist past, yet it required logic.
"I believe I am familiar with this earth 'game'," his father had said once, the last word rolling off his tongue distastefully. "A variation of it has been introduced to me by a Terran ambassador, who insisted I was bound to 'love it'."
Spock had been six years old back then, and his father just returned from yet another trip to earth. As Spock has long since began his education, he was unavailable to join him, and his mother has stayed behind as well. At the moment, she was telling Sarek over the dinner table how she's taken to teaching their child to play chess.
"I don't suppose you ended up loving it," Amanda laughed heartily and put a piece of the food his father has brought with him on her request. It was called 'cake' and held a rather dubious nutritional value.
"I find it less distasteful than several other earth pastimes, as it relies on logic rather than aesthetics and does not physically endanger the participants. However, I see no purpose in teaching it to Spock. Several exercises exist on Vulcan that would improve his intelligence more reliably."
"It's not an exercise, dear, it's a game," she said with sweet, sweet patience. "I wanted to show him something that has to do with earth culture, and he'll devour all this historical trivia with or without me around... Plus, it's fun, isn't it, Spock?"
"Vulcans do not experience 'fun'," Spock recited obediently, chin raised. His father looked at her with all the confidence that befitted this situation. She did, however, keep teaching him until he became too good for her to match. It took three whole weeks because of his busy schedule.
With the inadvertent help of Nyota, Spock has finally matched this incident to his current behavior. His desire to play chess held traces of sentimentalism which he could not afford. He decided the best course of action would be discarding the game completely, instead dedicating his time to the pursuit of knowledge, and he knew his father would agree if he were to ask him (except he would also warn him against asking questions he already knew the answer to and seeking emotional comfort, so of course Spock wasn't going to do any such thing).
He would let the humans to their conclusions. They most probably saw him play the game and glossed over it, thinking it was just what smart people did. He did not need to let it bother him further.
The following time period came to be dubbed 'After Nero' by most Vulcans. Many have temporarily let their mental defenses down to the point that calling it 'After Our Planet and Most of Our Race has been Destroyed' was too painful for them, and many others claimed that this title was impractically long and they had to call it something. The two groups overlapped with a surprising perseverance.
Whichever it was, most everyone was certain that Surak couldn't have anticipated a traumatic event on this scale. It was curious and futile to speculate about his thoughts on the matter. He himself would never voice it out loud, but he was of the opinion that if there could ever be circumstances that excused blatant emotionalism, then this was it - so long as it didn't make you nearly choke someone to death.
He did not know what disturbed him more, the efficiency with which Jim could elicit an emotional response from him, or how very quickly he'd forgiven the sheer violence of that response.
Jim Kirk, as if sensing Spock has been thinking about him, appeared outside the door of his and Nyota's quarters.
With a flick of his wrist, he turned off the screen that informed him of the visitor. "Come in," he said, and the door slid open.
The captain stepped in, waving a PADD with the kind of enthusiasm he only got after living on nothing but coffee for at least three shifts in a row. Spock briefly confirmed the estimation. The away mission ended just in time for a gamma shift, another gamma shift began seven minutes ago...
"Hey," the captain said. "Three-dimensional chess against yourself? Nice. Real intellectual of you."
He sank into the second chair in the room, the one that usually belonged to Nyota.
"Is there anything you require, sir?"
"Just came to tell you Uhura will be double-shifting tonight. I need those treaties translated as soon as possible, but for your information, she volunteered."
"I understand," Spock said reasonably. Perhaps something in the captain's and Nyota's interaction has sprouted the insistence, but then, the bright haired man rarely needed a reason to be inexplicable. "Is there anything else...?"
"Your report. No, don't look at me like that, you know you've done everything right. I just found a few discrepancies between yours and the one of that ensign and I thought it would be better to discuss it in person. I mean, since Uhura isn't here anyway and everything."
"Captain, I believe you realize that the human brain's memory forming facilities under the influence of adrenaline-"
"-aren't as awesome as yours. I can't go and call my ensign a liar just because he didn't remember whether the guy who was trying to vaporize him wore the local government's weird spiky armor or the resistance's weird spiky armor, and I can't just ignore the official report either. Which is why I wanted to sort this out in person. Hey, what's the queen doing?" He poked into the small holographic form. Nothing happened, as the computer was currently in possession of the white side.
"I suspect she is simultaneously defending the king along with the rook," he gestured towards the two-level formation that seemed to confuse Kirk, "And preparing for an attack on the lowest level."
"You suspect?" He scanned the board with the analytic gaze Spock had thought was reserved for politics and battle strategy. "Oh, so you're playing the computer. Does it ever win?"
"It always does - though only because I have written the program myself."
"Figures. Nobody else would put so much effort into 3D chess that it could actually outsmart you."
Ignoring what could possibly qualify as a compliment to his person and an insult to everyone else who has ever written simulations of 3D chess, he asked, "Do you dislike this variation of the game?"
"Not really. I just don't think there's anything wrong with playing normal chess unless you suck at it."
He has not expected the captain to have any particular opinion on chess - which was, frankly, stupid of him. His leader was a brilliant strategist, as much as he liked to veil this fact. Perhaps it was his apparent inability to sit still for any period of time that gave him this notion. "I assure you that I do not, in any meaning of these words, 'suck at it'. If you yourself are so well-versed in chess, perhaps you would join me for a game?"
"Sure, be coy like that. I actually haven't played for years, but yeah, it'll be my honor." He said the last bit ceremoniously, raising his PADD in a salut. "Why would you be playing chess anyway, Spock? Don't Vulcans have smarter games?"
"My mother liked chess," he informed him. "Now, I believe you wished to discuss my report."
They did play, later, and Spock won.