Chess--have I been here before? No, no, there.

Spatial reasoning.  That's what chess calls for.  What else?  Not so much the ability to forecast your opponent's next move, although this is vital, and requires you to think about your weaknesses potentially too much, and become incompetently unwilling to take an offensive risk, or even know that one should be taken, but the ability to see how the board will change once a piece is moved.   I don't mean that lightly.

It goes like this.  You have to make a move.  Your move is predicated on the set of potential moves that your opponent may make in response.  Your question is what their most likely move is given your two best options for moves forward.  Once you determine their response, though, and this is the hard part, you must make the calculation again, this time by pretending that you've teleported yourself into the future now sit in front of a board with the initial move and response.  The error--always the error--is to think about the board in the potential future state as if you never made an initial move, and instead focus in on what your oppontent did in response.  It is the trap of binary thinking, really--either you think about your move and then their response as isolated, or having moved (in your head) you think about their response to your move, and then your response to their [response].

The problem (nay, the accident) is that you forgot all about your own initial move, often, at least, and the game you're playing is now blindsided because you don't visualize the future board with two or three changes, but just the one that your focused in on.

That's because every move opens and closes a slew of possibilities on the board.  Perhaps, based on one explicit conflict, it is easy enough to match up forces and imagine the exchange as a one-piece-for-one-piece sort of thing.  But that's precisely not what is going on.  Instead, what is going on is a potential opening and closing of sixteen piece conflicts at every move--some may appear immobile at the outset, for instance, and we use a mental shortcut by locking them out of our calculation for the first move we setup--except that, by the third move, they'll play a role!  "Revealed check" is my favorite.  You move a piece that allows a different piece to check the King, and you simultaneously threaten a third piece--you force your opponent to react to your game.

All very heady, I know.  If I was only smart enough, or had enough training, to actually understand the game.   I'll stay a hopeless beginner long into my life.  Still, that's okay.  I never had enough discipline to study it anyway.  That's the way we make cacluations.  At some point, unless I manifested a natural brilliance (which I didn't and never will) for chess, the likelihood is that I will not specialize in, and make my living from, chess.