[disordered]

I don't agree with your premise that chess has evolved to be at the pinnacle of its niche (I don't know enough about Go to comment on it). There are a number of interesting variations in chess-like games that, while maintaining the general theme of killing the enemy king, offer aspects of gameplay that chess does not.

Two of the more well known variations are shōgi and xiangqi: Shōgi allows the redeployment of captured pieces, whilst xiangqi limits the movement of a few pieces and has a mechanism for representing artillery. I find that each game has a very different character to that of western chess, even despite the fact that they share a large number of tactical motifs.

Western chess may be the most popular variant world-wide, but that's no indication that it is at any kind of pinnacle.

[michaelscott]

I think it's fair to call it the pinnacle when talking about the Western world. Both shogi and xiangqi developed from the same base game as chess historically, so I'm not sure how far they venture from the theme compared to something like hnefatafl (which is chess-like but varies considerably in game mechanics when compared with shogi and xiangqi).

[kd5bjo]

Just like Like Go and Poker each have a number of variant rule sets in common use, I mentally group all of these as “chess” based on their common ancestry. I haven’t really studied them enough to know if this is truly justified.