Gamemaster Environments (IF)

Hard Science-Fiction Setting

The Solar System is full of dangerous places and environments.

Gravity Environments

Gravity in the Solar System conforms to four categories, with only a few man-made exceptions. These categories are used both for training and as categories of genetic or mechanical modification. No celestial body in the Solar System has a natural surface gravity between 0.4 g and 0.8 g or above 1.2 g.

Microgravity Near-weightlessness, such as spacecraft in freefall. Focus is on orientation, translation, tool use, and stability. Days of exposure cause Degrav.

Low Gravity 0.15–0.40 g (e.g., most moons; borderline worlds like Mars and Mercury at ~0.38 g). Emphasizes balance, momentum control, assisted locomotion, and jump/braking control. Degrav risk over weeks to months.

Low Gravity 0.15–0.40 g (e.g., most moons; borderline worlds like Mars and Mercury at ~0.38 g). Natural locomotion shifts from walking to bounding/loping — long, low jumps conserve momentum to cover distance with little effort. Distinct from Microgravity where there’s no footing at all. Degrav risk over weeks to months; periodic Regrav prevents long-term loss.

Low Gravity 0.15–0.40 g (e.g., most moons; small planets like Mars and Mercury). Natural locomotion shifts from walking to bounding/loping — long, low jumps conserve momentum and cover distance with little effort. Distinct from Microgravity where there’s no footing at all. Degrav risk over weeks to months. Beware overshooting on slopes and kicking up regolith plumes that hang in low-g.

Earth Standard Gravity 0.8–1.2 g, considered healthy for long-term residence. Covers most living areas of Artificial Gravity habitats and the surfaces of Earth and Venus. Focus on endurance, load-bearing, and efficient movement.

Aquatic Submersion in water or other liquids. Includes maneuvering by swimming or with specialized equipment. Ranges from shallow habitat lakes to high-pressure oceans. Not strictly a gravity category, but the same issues of movement and posture applies.

Terrain Terrains

Earth has many terrains (all at Earth Standard Gravity) characterized by abundant life: vegetation, fungus, and animal ecologies. To spacers this is like a land of fairytales — beautiful, but dangerously unfamiliar. The Earth is greener than it has been in a thousand years.

Extraterrestrial Terrains

The variety of domains off Earth is narrower, but each is deadly in its own way. Most are in low gravity or microgravity; only Earth and Venus offer long-term Earth-like gravity. This list covers terrains common across the Solar System (not unique local oddities).

Regolith

Airless-world “sand” and dust are insidious. With no wind or water to round grains, particles are sharp and piercing, wearing down suits and machinery. Electrostatic charging makes dust cling to everything and can disrupt electronics and radio. It gives poor purchase for boots or tethers. In microgravity it offers almost no purchase and forms dangerous, long-lived dust clouds — over time these turn into micrometeors that can puncture suits and hulls. The composition of regolith varies by location, subtly changing how it behaves and adding unpredictability.

Ice

Common from ring grains to kilometer-thick glaciers. Heat causes sublimation in vacuum; even local warmth makes surfaces slick. Ice undergoes harsh cryotectonic flow, raising pressure ridges and deep crevasses that shift over time. Fracture produces knife-edged shards that cut suits and lines. Rare exotic high-pressure phases can behave unpredictably to tools and sensors.

Rock

The least capricious footing is competent rock or metal — good for anchors and traction. Its permanence preserves ancient cracks, thrusts, lava tubes, and paleo-channels. On worlds with past volcanism or water, tunnels and canyons provide shelter and traverses. Provides reliable anchors for magnetic accelerators.

Vacuum

Away from planetary bodies — and on many surfaces as well — vacuum is the default. Problems include:

• Atmosphere: you need an air supply (short-term) and recycling (long-term).
• Pressure: you need full-body pressure protection; mechanical counterpressure suits can be thin but still require complete coverage and a helmet.
• Mobility: no buoyancy or aerodynamic control; you must manage translation via tethers or reaction mass, obeying conservation of momentum.
• Short emergency exposure: If suddenly vented, do not hold your breath — exhale immediately to prevent lung injury. Expect loss of consciousness in ~10–15 seconds from hypoxia; rapid recompression and oxygen can prevent lasting harm. Unprotected skin can swell and chill but usually endures brief exposure; eyes and ears are vulnerable (pain, drying, potential injury) — even minimal eye protection and an oxygen mouthpiece or nose clip dramatically improve survival for dash-length gaps between airlocks.

Outer Space

There is no “empty” space — there is always debris, fields, and radiation. Micrometeors are a constant threat, especially near regolith bodies or old work sites. In sunlight you face radiation and, in the inner system, intense solar storms; in deep shadow there is no natural light to navigate by. With no traction, attitude can be changed by body motion, but changing position requires tethers or thrusters. There is always microgravity.

Orbital Space

Near a planet or moon, you don’t fly in straight lines — you change your path and wait for the result. A prograde burn makes your track swell outward; a retrograde burn makes it tighten — the effect shows up later along the orbit. Thrusting toward a target doesn’t move you closer — it skews your course and you drift. To match trajectories you don’t aim at the target; you slip onto an intersecting orbit, then make final adjustments so you slide into a nearby parallel path instead of hitting. Unless you’re a real pro, let your navigation system do the planning.

Drop to catch up, climb to fall back, fine-tune to intercept

— Spacer proverb.

Spin Habitats

Rotating habitats mix spin gravity — almost always Earth Standard Gravity — near the hull with microgravity near the axis. Kinetics are non-intuitive: Coriolis deflects trajectories significantly. Firearms and thrown objects become unreliable beyond short ranges (often only tens of meters); aiming requires local tables or smart sights. Besides these familiar environments, two unusual “terrains” emerge:

• The interior volume between axis and surface: if you leave the surface, you stop corotating; the floor appears to shear sideways beneath you. With skill, you can “ballistically” hop to distant points — if your aim and braking are precise.
• The outer hull: outside a cylinder there is no spin gravity, but relative motion is tricky. Let go and you drift along a tangent while the hull rotates away; hovering over a spot requires continuous correction or magnetic/grapple anchoring. Small Jovian EVA rigs often use “feet” with magnetic or grappling pads to stay planted.