Lost In Blue 2 - Serious Survival mode

Another house location:
Go far in the jungle to find a grassy place. You can make another house there.

Getting food and firewood:
You can ask your partner for food and firewood. When you have 40 or less, tell her or him to get food or firewood.

The ruins: Hidden area
If you look closely on the walls of the ruins, you will notice what appear to be old style fire pits. Light these with your torch. The wall will open up and you will gain access to a new room. One way will be a new exit to the swamplands. Two openings will lead you to rooms that have huge pedestals that must be lit with your torch. You must do these in the order as they appear one after another. They will lead you all over the island.

Sleep:
You can only go to sleep if you do not have 0 for water and food. However, that only applies to your character. The game will still let you and your partner go to sleep if you at least have 1 for food and water, even if your partner is at 0. You can both rest to fill up the stamina meter as long as the character you're playing has food/water. Hold the partner's hand to rest.