Which game is a chess variant, Ubongo or Ouk-Khmer?
Ouk-Khmer (Hill's version) Ouk-Khmer (also known as Cambodian Chess) is a chess variant which D. B. Pritchard claimed was played in Cambodia although its actual origins appear to be unknown. Pritchard gives the source as P. A. Hill. It combines elements of makruk and xiangqi. Similar to xiangqi, it is played on the intersections of an 8×8 monotone board (Instead of 8x9). Contrary to Pritchard's claim, the actual variety of chess played in Cambodia today, known as "Ok" or "Ouk Chatrang" is nearly identical to Makruk. The authenticity of the game described by Pritchard remains doubtful.
Irregular chess opening In chess, irregular opening is a traditional term for any opening considered unusual or unorthodox. In the early 19th century it was used for any opening not beginning with 1.e4 e5 (the Open Game) or 1.d4 d5 (the Closed Game). As opening theory has developed and openings formerly considered "irregular" have become standard, the term has been used less frequently.