Complex sentence: The last major element of many "BRP" games is that there is no difference between the player character race systems and the monster or opponents, an element that is shared with and originated in "Tunnels and Trolls".
Split into simpler sentences: The last major element of many "BRP" games is that there is no difference between the player character race systems and that of the monster or opponents. This element is shared with and originated in "Tunnels and Trolls".