At the beginning of each game you get three lives. When you lose all three of them, the game is over. You vitality level can become depleted. After that, you get an extra life for each additional 70,000 points. The points you earn for finding certain items and defeating different enemies are added together to produce your final score.
Some items are also worth additional vitality points.
The number of points you get is determined by how much vitality you have and by how many dolls you've collected. When you clear an area while being possessed by the god of death, you will get additional 1000 bonus points. When you're in the clouds, you have the opportunity to increase your vitality by getting Tanya's heart. You can jump off the cloud and go back to another area of the game. You can wait untill your vitality runs out.