Although there are several examples from games in the 19th century, the Van 't Kruijs Opening is not popular in the modern era and is not a common choice for grandmasters, but its ability to transpose into many different openings explains its attraction for some players such as Pavel Blatny, Aron Nimzowitsch,[1] and Bent Larsen. Benjamin & Schiller (1987) call it a "chameleon". According to ChessBase, it ranks sixth in popularity out of the twenty possible first moves.[2]
The loss of popularity is due to 1.e3 gaining little except as a transposition strategy to reach other positions.[3][4] It releases the king's bishop, and makes a modest claim in the centre (supporting a future d4), but the move is somewhat passive compared to the much more common King's Pawn Game (1.e4). The queen's bishop's development is somewhat obstructed by the pawn on e3, and White usually wants to take more than a modest stake of the centre.
Benjamin & Schiller's (1987) general advice is to watch out for transpositions and suggest a 1...g6 fianchetto response since e3 positions against fianchetto are weak. The most common response after 1.e3 is 1...Nf6, where White generally continues with 2.Nf3, effectively transposing to the Reti Opening. Here, White can either play d4 soon after, potentially transposing to a Queen's Gambit Declined line, but can also deviate with a system similar to the Hedgehog System played by Black, with b3, c4, Nbd2, and Be2.
If Black responds with 1... d5 or 1...c5, White can respond similarly to 1...Nf6. Even 1...b6!?, 1...g6!?, 1...c6!?, or 1...e6 is completely playable. Another common response is 1...e5, where White usually plays 2.d4, transposing to the French Defense Exchange Variation after 2...exd4 3.exd4 d5. However, either White or Black can deviate, showing the flexibility of this opening.
Other moves like 1...b5?, 1...g5?!, 1...h5?!, or 1...a5?! are rarely played.
There are also a few experimental moves that can be tried. For example, after 1.e3 e5, White can play 2.e4!?, therefore making it a reversed Open Game. This is often used when White has much knowledge of the opening when playing as Black. Therefore, this can be used to ensnare a few opponents into traps. However, since this gives the first move advantage to Black straight away, this is not recommended. Similarly, 1.e3 f5 2.e4 goes to a reversed From's Gambit, where White is practically playing as Black.
^
Chess Informant (1979). Encyclopaedia of chess openings. Šahovski Informator. p. 12. Chess Informant considers the position even (=).
^Griffith, RC; White, JH (1939). Fine, Reuben; Griffith, RC; Sergeant, PW (eds.). Modern chess openings (6 ed.). D McKay. p. 87. Fine et al. highlight these Nimzovitchz–Tarrasch moves as the main line and considers this position as even.
