Can you tell me what is the end of Poly?
it means the protagonist can end up with both love interests instead of choosing only one
And how do I open it?
do you mean opening the game itself or achieving the poly ending?
achieving the poly ending.
You have to choose an equal amount of choices between them. If you choose a choice where you interact with Percy, choose Gavin the next day. Then you repeat the process.
OK thanks for the info
