Shoot down passive creatures during the day, before they turn into monsters at night. Fight off police officers that attack you along the way. As days of the week pass, you will unlock new areas and buildings to explore.
Anything you left alive during the day is now a monster. Your guns don't work against them. All you can do is run, hide and survive with only a torch, and a laser pointer. KILL THEM WHILE YOU CAN.
Explore the beach town to gather the materials you need to escape. Find materials in different buildings that open up throughout the week, and after Wednesday, you can use the shop to buy weapons and sell excess materials.
I don't think the sun is real has a focus on short playthroughs with multiple endings. Escape whichever way you choose, with each escape method requiring different materials. Each method of escaping has its own ending, plus a one or two secret ones...
"I know that something isn't quite right... I just have to leave this place."