I'm sorry for my bad language expression. The core gameplay is survival, I like survival game. And plot or missions are not mandatory to finish.
Viewing post in Need some inspirations and ideas
It's alright :)
There are many ways to expand a survival game. But I'm going to focus on your idea about finding truth. What about this: player wants to find the truth by going to the tower or whatever the light source was but it has to be done by traversing forest and wilderness. And it can only be done during daytime only. If sun has set, player must camp and survive the night to continue the journey the next day.
So the gameplay would be : travel during the day and camp during the night. However, it's not that simple cause wild animals could attack during the day and player needs weapon to defend themselves. And of course, player needs food and water to survive. These resource gathering and crafting takes time so player need to strategize when to do any of them.