The goal was the Boss :P After 10 waves the boss spawns. This bug happens if you click to fast :P I got that too. And the ghosts have different abilities: white melee, blue melee but stronger, yellow ranged, green summoner who spawns blue ghosts. I would say you got unlucky, after two three deaths you should have about 12-20 points and in later waves you get crystals which are more points worth.
Thank you for playing :D