The Iron Rule

Nine miles of green, and a box of rations that will not last it. Walk east.

A world can be lush and still be a desert to you. Calories are not a property of a place — they are a property of the match between a place and the body that arrived, and the only thing you can eat is the thing you brought.

Walk east

The Hearth is nine miles that way. Everything green out here grew up mirror to you: most of it will go down, sit there, and feed you nothing at all.

Hold the mouse (or WASD) to walk. You pick things up by walking over them.
E — eat what is in your hand. Hold T — taste a sliver, and know that kind for good. You have to stand still to do it.
Space — fire. Eight rounds came down with you, and the animals out here are the one reliable fat in this country. Missing costs the same as hitting.
R — a ration from the pod. You have three. Q — throw away what you carry.

Watch both bars. Full is what your belly knows. Strength is what your body actually got. They are not the same thing, and only one of them kills you.

Crossing #1. Everyone who walks today walks the same country.

Where the rules come from

“Elpis life arose independently and, crucially, uses the opposite chirality — mirror-image sugars and proteins to Earth's.”
“A starving survivor surrounded by lush ‘food’ can still starve.”
“Fats and oils are far less handed, so certain native lipids ARE metabolizable.”
“Some tissues are safe as water/roughage but give no calories — they fill the belly and quiet the mind while the body still runs down.”
“A tested sliver and a whole shaking day of waiting before she'll risk a bite.”
“A hard freeze breaks the toxin down… a hope with a date on it.”

All from the Otherworld Story Bible, §4 and §5, where the Iron Rule is marked load-bearing.