You must live on the island for 30 days.

Your vitality is constantly decreasing and also while you are sleeping.
In order to survive, you need to constantly eat and drink water.
Many actions take more HP: jumping, climbing trees, swimming, swimming in the swamp. Also, rain and wind take HP, depending on their strength.
To protect yourself from rain and wind, you can build a tent from the nipa that grows on the island.

For hunting and protection you can use stones.
if you catch a stone after a throw(Up), it can be used again

Subtraction of HP per night depends on several factors. Whether it was rain or wind at night, whether you slept in a tent.

If you sleep in a tent, HP deducted per night is 50.
You can only sleep on land. If at night you find yourself in water, the HP subtracted per night will add +500.

When your HP reaches 1000, super power mode will turn on. You will become stronger, you can move faster and jump higher and throw stones further, but also this mode will pick up + 1HP every second additionally.

Keyboard controls:

Left – Arrow Left, A 
Right – Arrow Right, D
Up – Arrow Up, W
Down – Arrow Down, S
Jump – Spacebar, Shift
Throw a stone – E, rControl
Choose a tent – T
Pause – lCtrl, Pause
Drink water – Down
Enter the tent – Up