In Hard Mode you have a thirst and hunger bar, as the day goes on you get hungry and thirsty, click the dead rabbit to fill your hunger and click the puddle to drink, when you are able to go out, hunt and click the river to survive. In Easy Mode, you will still have the hunger and thirst bar, but they won't go down, so you won't die because of that. Move with arrow keys and talk to your parents every day. Enjoy! (tell me if the bird sound is annoying XD)
