The rules are informally known as the "New York style" of baseball, as opposed to other variants such as the "Massachusetts Game" and "Philadelphia town ball".
Modern scholarship has cast doubt on the originality of these rules, as information has come to light about the New York clubs that predated the Knickerbockers, in particular the rules devised by William R. Wheaton for the Gotham Club in 1837.
Baseball historian Jeffrey Kittel has concluded that none of the Knickerbocker Rules of 1845 was original, with the possible exception of three-out innings.
[1] Nonetheless, the Knickerbocker Rules are enormously significant for baseball historians because they are the earliest extant rules from which the evolution of modern baseball can be lineally traced, and whether or not they can claim to be "first", certainly describe the kind of game played by the New York-area amateur clubs from which the modern game developed.
The list as presented, except for the commentary, is taken directly from the "Rules" as published in the 1860 Beadle's Dime Base Ball Player, edited by Henry Chadwick (website below): 4th.
The game to consist of twenty-one counts, or aces; but at the conclusion an equal number of hands must be played.