You, who needed money, will participate in a secret biological experiment. You will play a 'Game' in a huge cellar for two weeks and have to survive the attack of numerous 'Entities'. What are those 'Entities', and who is waiting at the top of the cellar?

You, who needed money, will participate in a secret biological experiment. You will play a 'Game' in a huge cellar for two weeks and have to survive the attack of numerous 'Entities'. What are those 'Entities', and who is waiting at the top of the cellar?