Question: What is similar of Shatranj and 18XX? 
Sentence (from "18XX"): 18XX is the generic term for a series of board games that, with a few exceptions, recreate the building of railroad corporations during the 19th century; individual games within the series use particular years in the 19th century as their title (usually the date of the start of railway development in the area of the world they cover), or "18" plus a two-letter geographical designator (such as "18EU" for a game set in the European Union).
Relevant evidence: Yes