"Project Vostok" is a non-linear horror visual novel about a group of airplane crash survivors finding a mysterious Soviet-era bunker in the Russian mountains.

A plane flying from Moscow to Barnaul crashes in the Altai Mountains because of a crew error. Almost two dozen strangers are left there to survive. An indefinite list of their problems includes injuries, lack of food, risk of being frozen to death, and conflicts within the group.

Things take a massive shift when the survivors find an abandoned Soviet bunker built in a cave. Warm rooms and an abundance of supplies lead them to move to this mysterious location. However, it soon turns out that all the problems they have encountered earlier were nothing compared with what is awaiting them now.

[Edited from Steam]