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--- a/ruby/README.md
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@@ -1 +1,16 @@
 Implementing HP {48,49,50} minehunt game
+
+You start on the top-left corner and your goal is to reach the bottom0right corner without blowing-up a mine.
+
+You can move using
+  ↑
+← ↓ →
+
+or (better) the keypad which moves as
+                7 8 9         ↖ ↑ ↗
+                4   6         ←   →
+                1 2 3         ↙ ↓ ↘
+
+You can quit at any time using 'q'
+
+You can replay at the end using 'r'