Each Life left is 10pts per Wave. That is added to How Much Gold left Per wave. It also records Gold Per wave and adds it all together at the end and adds that total to the score (So higher scores? Wait to spend between waves.). I'm not sure how much the enemies are scored though, whether it's gold they give or Exp they give. You get points for each gold spent (but if you want the higher scores wait for in between waves if you can)
 "The Enchanted Cave 2"){kind=icon}
 "Protector III"){kind=icon}