"The first time I played chess I tried to move my…

There are two players in the game of chess (players with white pieces and black pieces), and each player has two rooks (or “castles”). A rook moves in straight lines, but not diagonally.

“The first time I played chess I tried to move my castles diagonally. Classic rookie mistake” is a joke that was posted on Twitter by Adam Roberts on March 27, 2011.

Wikipedia: Rook (chess)
A ,i>rook (/rʊk/; ♖,♜) is a piece in the strategy board game of chess. Formerly the piece was called the tower, marquess, rector, and comes (Sunnucks 1970). The term castle is considered informal, incorrect, or old-fashioned.

Twitter
Adam Roberts
@arrroberts
The first time I played chess I tried to move my castles diagonally. Classic rookie mistake.
11:20 AM - 27 Mar 2011

Twitter
Ian Power
@IHPower
Whilst playing chess for the first time, I embarrassingly tried to move the castle diagonally. Rookie mistake.
12:50 PM - 26 Aug 2011

Twitter
Scott Washington
@scottwashi
In chess, moving your castle first would be considered a ROOKie mistake.
12:35 PM - 18 May 2012

Twitter
Scott Myц
@ScottMuc
A moment of punspiration! Q: What do you call it when you castle incorrectly in chess?
A: A rookie mistake
4:32 PM - 13 May 2013

Twitter
Boomtastic
@boomtastic
The first time I played chess, I thought the castles moved diagonally.
Rookie mistake.
8:01 AM - 18 Apr 2018

Twitter
Harry
@GhostOfGreenSt
I’ve only just started playing chess and I keep trying to move the castles diagonally. Rookie mistake.
#1PUN
5:00 AM - 27 Apr 2018