It was invented by Edward de Bono in 1967 where the author presented the game in his book The Five-Day Course in Thinking.
The game is easy to learn with simple rules. The full detail on how to play the game can be found at the wiki page https://en.wikipedia.org/wiki/L_game .
Detail of this game:
It is a two-player game played on a 4x4 board. There are only two types of pieces. The first type is the 2x3 L-shape piece and there are only two pieces of L on the board. It is also why the game is called L game. The second type is the 1x1 dot piece and there are also two pieces of dot on the board.
Each player takes turn to change his/her L position (either the red or the blue L) and the L must be in different position than the initial position. Then he/she can move the one of the dot to any empty square or skip by giving up the right to move the dot.
The goal is to block the opponent until there is no more move for the opponent where the game ends and a winner is determined.
The human players can compete against each other or against the built-in AI (Artificial Intelligence) engine. They can choose to be the red or the blue (or who to start first) when matching against the computer. At each turn, the player knows how many valid moves he/she has.
It is even possible to watch the AI engine play against itself. Sometimes, it is very thrilling to watch computer beating computer. :)
The human player can also ask help from the AI engine if he/she is stuck in the game.
There is an option to undo a step or even the whole match. This allows the player to study the game step by step.
The only game that is fair to 1st or 2nd player and goes on forever if both players play the perfect game.
I loved this game when I was young. Good little app well done.