There is no such thing as a typical Earthlike planet; every world is unique. To reflect this, some earthlike or marginal planets will have one or more "special features" that are not covered by the usual planetary parameters. Roll a D100 three times on the following table to determine what the features are. If you get the same result (other than "No special features") twice, roll again.

Most features are restricted to planets with certain properties (for example, the "Freshwater oceans" feature requires a non-zero ocean percentage), or are incompatible with certain other features (for example, a planet can't have both "High inclination" and "No seasons"). See the detailed descriptions below for explanations of the incompatibilities and prerequisites. If you get an incompatible result, roll again.

GMs are encouraged to let their imaginations run riot in expanding this Table.

ECCENTRIC ORBIT: The planet's orbit is highly elliptical, producing extremes of temperature at closest approach (periastron) and furthest distance (apastron). Incompatible with "No seasons".

HIGH INCLINATION: The planet's axis is tilted by more than 45 degrees, producing extreme temperature differences between summer and winter. Incompatible with "No seasons".

HIGH TIDES: A large, close moon or sun produces extremely high tides. Requires either a K-type sun or at least one moon.

METEOR STORMS: The planet suffers frequent meteor storms, often including large asteroid or comet impacts, making the planet's surface a dangerous place. Marginal planets only.

NO SEASONS: The planet has close to zero axial inclination and orbital eccentricity, so there are no seasonal effects. Requires a single star; incompatible with "Eccentric orbit" or "High inclination".

RINGS: The planet has a natural ring system.

RADIATION HAZARD: Radioactive minerals, or fallout from a nuclear war, create a significant radiation hazard over parts of the planet. Marginal planets only.

RUGGED TERRAIN: The planet's land surface is almost entirely covered with mountains and rough, rocky terrain, with practically no flat plains or rounded hills. Requires an ocean percentage less than 100; incompatible with "Swampy surface".

VOLCANIC ACTIVITY: The planet has many active volcanos, enough to make life dangerous over a large part of its surface. Marginal planets only.

FRESHWATER OCEANS: The planet's oceans have very little salt in them, either because they're geologically young or because some life form has affected their composition. Requires a non-zero ocean percentage.

MANY ISLANDS: The planet's land surface is broken up into a large number of small islands, with no large continents. Requires an ocean percentage greater than zero but less than 100.

POISONOUS OCEANS: The oceans contain some contaminant or (more likely) life form that makes the planet's sea water poisonous to humans. Marginal planets only; requires a non-zero ocean percentage.

SWAMPY SURFACE: Most of the planet's land surface is low-lying and covered with swamps, marshes, mud, quicksand, and so on. Requires an ocean percentage less than 100; incompatible with "Rugged terrain".

CLOUD COVER: The planet has a permanent cloud cover over its entire surface; it probably rains most of the time. Requires a temperature greater than zero degrees Celsius; incompatible with "Very thin atmosphere".

TOXIC GAS: The atmosphere contains some gas which is poisonous to humans, making filter masks necessary. Marginal planets only.

UNSTABLE CLIMATE: The climate undergoes severe and unpredictable changes from year to year.

VERY DENSE ATMOSPHERE: The atmosphere is dense enough to be unbreathable without special respirator equipment, except perhaps on very high mountains. Marginal planets only; incompatible with "Very thin atmosphere".

VERY THIN ATMOSPHERE: The atmosphere is too thin to breathe without special respirator equipment, except perhaps in very deep valleys. Marginal planets only; incompatible with "Cloud cover" or "Very dense atmosphere".

INTELLIGENT LIFE: The planet has a native sentient life form, which may or may not have advanced technology. Requires advanced invertebrates or higher life; incompatible with "Semi-intelligent life". Less likely with life other than advanced vertebrates (25% chance, otherwise roll again).

SEMI-INTELLIGENT LIFE: The planet has a native life form which is not fully sentient yet, but comes close, and may develop further. Requires advanced invertebrates or higher life; incompatible with "Intelligent life". Less likely with life other than advanced vertebrates (25% chance, otherwise roll again).

WORLD FOREST: The entire land surface (except perhaps ice caps) is covered by a single huge forest. Requires an ocean percentage less than 100.

ANCIENT ARTIFACTS: Artifacts left behind by aliens, thousands or millions of years ago, exist on the planet.