diff --git a/README.md b/README.md
index 87e0512..6e0732d 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,11 @@ There are 55 marbles on the board, composed as follows:
 - 5 pieces of Mercury
 - 4 pairs of Vitae and Mors
 
-Your goal is to clear the board. 
+Your goal is to clear the board. For a marble to be removed, it must be combined with 
+another suitable marble. Further, it must have *three or more contiguous free tiles* 
+around it.
+
+**Reaction rules:**
 
 - Vitae reacts only with Mors
 - Elements react with the same element kind, or with Salt
@@ -27,7 +31,7 @@ Your goal is to clear the board.
 - Metals react with Mercury, but they unlock one by one, from the most common Lead to Gold.
 - Gold is removed by itself as the last metal
 
-The metals sequence is as follows:
+**The metals sequence is as follows:**
 
 1. Lead + Mercury
 2. Tin + Mercury