Under a Hostile Sun is an RPG about surviving in brutal environments.

It is not monsters you need to overcome – but nature herself is your enemy. The early explorers faced terrors – starvation, ice, heat, hurricane, and disease. In the future, faster-than-light travel exists – but that does not change the fact that colonizing an off-world planet is brutally difficult.

It’s not uncommon for whole crews to fail in their attempts to settle a new world. These planets are too close to their nearest star. Or have atmospheres filled with acid. Or are defined by never-ending storms. Or . . .

But despite all that, you believe you have what it takes to survive. Your fellow colonists stand against a common enemy – a cosmos that has swallowed beings greater than us and seeks to swallow you.

But with firm faith in the Immutable, and each other, maybe you will live to see the sun rise on this world, not as an existential

Building an Explorer

Archetypes

Game Modes & Goals

Hostile Environments

Alchemy

Alien Creatures

Rolls are done on a d20. The result is compared to the relevant stat (see Building an Explorer ). Under the Stat is a success. Equal to the stat (“right on target!” or “Crit!”) is a critical success which the GM may reward with extra benefits.

The amount of Resources the party has mined from the planet is abstracted as Game Currencies. These are:

• Odd Ore - Geological, Mined with Might - Associated with Metal, Stability and Protection, bending of the Laws of Physics, Might Actions
• Arcane Algae - Botanical, Mined with Agility - Associated with Water, Psychological effects, aquatic mutations, Agility Actions
• Strange Sap - Botanical, Mined with Focus - Associated with Wood, Mutation, plant life, terrestrial adaptations, and Focus Actions
• Molten Minerals - Geological, Mined with Tech - Associated with Fire, explosives, energy, heat, Fuel, and Technological Actions
• Helpful Herbs - Medicinal, Mined with Compassion - Associated with Earth, Healing, growth, medicine and Compassion Actions

The party will regularly tame and cooperate with alien beasts. To keep the zoology simple, most beasts are summarized as follows:

- A buff the beast gives its tamer. - A pool of stat points that can be spent to reroll a check for a given stat. - A Basic Resource it uses as food to recharge its pool of stat points. This is called Food Cost. - An Elite Resource it can make, if given the correct Basic Resources.

This is a rules-light exploration focused game. As such, there will be lots of grey area for GM interpretation. Trust your gut, rulings not rules! There will be the most dice rolls / rules during Hostile Environments.