Career
At the first Nordic Chess Championship held in Stockholm 1897, Collijn responded consistently against 1.e4 with 1..d5. This chess opening, at the time known as the Centre Counter Gambit, is now commonly referred to as the Scandinavian Defence, a term documented since 1994. They subsequently authored a publication of annotated games of interest from the Stochholm Congress.
Ludvig was a cousin of Isaac Collijn.
In 1896 the brothers authored their "Textbook of Chess", i Schack. According to Hooper and Whyld, the fourth edition of Collijn"s (in Swedish), with groundbreaking contributions by Rubinstein, Reti, Spielmann and Nimzovitsch was one of the "popular reference sources for strong players between the two world wars".