feat(README): talking about my approach

README.md

@@ -8,7 +8,7 @@ RL on this challenge.
 
 ## Presentation of the puzzle
 
-The original game is played on a 16x16 board, where each piece
+The original game is played on a 16×16 board, where each piece
 has 4 specific colours on its sides. The goal is then to place
 each tiles on the board so that each tile's sides perfectly match
 the colours of its neighbours.
@@ -18,3 +18,21 @@ partial solution has a total of 467 matches out of the 480
 total perfect matches.
 
 More can be found at the [wikipedia page](https://en.wikipedia.org/wiki/Eternity_II_puzzle).
+
+## My Approach
+
+An episode starts by randomly scrambling the pieces
+and then the agent have a limited number of steps to
+rearrange the pieces as best as possible.
+
+I train a policy agent to swap pieces of the puzzle.
+When swapping the pieces, the agent can rotate them
+to properly align the sides with their neighbours.
+
+The reward is based on the number of matching sides,
+and can be given during the episode or only at the end.
+
+To try my ideas faster, I start by solving easier
+versions of the game, the simpler being a 2×2 board.
+
+![A 2×2 board being solved by an agent](./.gifs/trivial_A.gif)