When I had journeyed half of our life's way, I found myself within a shadowed forest, for I had lost the path that does not stray.
Your character died at the wrong time, before they were ready. Now they are shades, traveling through a forest in search of a promised place where they can ferry across a river and return to life.
They will start their journey by being sorted into groups. The characters in each one serve as the anchors for each others’ souls -- emotional distance from them results in breakdown of the soul, and closeness results in strengthening. With their teammates, characters need to compete in various games and challenges. Some begin as blank slates: they start as amnesiacs, and winning these games will help them regain the memories they've lost. Others come in as they are: they are in possession of their memories, but losing games will cause these memories to be lost as well.
As they travel, the path grows darker and the way grows more and more dangerous. All the while they have one goal above all others: have enough of themselves left to cross over back to life by the time they reach the river crossing at the end of the journey.