RimWorld is an indie top-down construction and management simulation video game by Montreal-based developer Ludeon Studios. Originally called Eclipse Colony, it was initially released as a Kickstarter crowdfunding project in early access for Microsoft Windows, macOS, and Linux in November 2013, and was officially released on October 17, 2018. The game has received generally positive reviews from critics.

The game has a small variety of scenarios to choose from, although the core gameplay is the same. The player characters (referred to as “pawns” in game documentation) are stranded on a planet located in the frontiers of known space (a “rim world”). The characters have a randomly generated set of traits which affect how they can contribute to the colony, the decisions they make, and how their existence affects the other characters. As time goes on, more characters will join the colony. Characters can be rescued after crash-landing on the player map, they can wander in, or they can be captured after a raid. Thus said colonists might also contain negative traits such as being pyromaniacs or psychopaths.

The game can end when at least one character has escaped the planet on a spaceship, or when they are all dead. With the Royalty DLC, the game can also end by hosting the High Stellarch, leader of one of the factions that inhabit the Rim, and leaving the colony with them.

The objective of the game is to ensure the survival of a colony of people, fighting against various environmental and/or internal events. Much of the difficulty as well as the critical acclaim for the game come from its unpredictability, through randomly generated events, and its extensively designed and customizable world. As the game progresses events become progressively harder and the player can unlock more advanced technology through research. The game has a top-down, two-dimensional view.

Random event generation
In-game events are randomly generated by an AI storyteller, which is central to gameplay; game difficulty, event difficulty and difficulty progression depend on its settings. The game has three preconfigured AI storytellers, “Cassandra Classic”, “Phoebe Chillax” and “Randy Random”. There are 6 different preset difficulties to choose from along with a custom difficulty option. These influence the severity and frequency of events as well as the good, neutral, and bad balance of events.

The game also has two save-modes. Commitment mode acts as Rimworld’s permadeath mode, disabling manual saving, and Reload anytime mode allows the player to save and load freely, giving the player a chance to undo an event.

The characters’ stability is represented by a mood meter, affected by basic or complex needs. Characters require food, rest and shelter but will also request a place to sit while eating, well made and undamaged clothes, or enough time for recreation like stargazing, cloud watching or playing chess. If needs are left unmet, characters may undergo “mental breaks” such as going into a daze or even going berserk and attacking other characters.

With the release of Alpha 13 on April 6, 2016, a new social aspect to the game was introduced. Characters were given the ability to have social relationships with each other, and an opinion system was introduced. These relationships can benefit or detract from the needs and joys of a character, and poor social relationships may result in fights.

In-game animals may also be controlled by the player, after being domesticated or tamed. Certain animals may be taught commands, which vary from simply obeying its master to defending them if attacked to occasionally carrying and storing items.

Technological progress
Another large aspect of game-play is technological progression. Players may harness electricity, which unlocks a plethora of machines and increases the colony’s efficiency, but they are forced to find ways to generate electricity, including wind turbines, solar panels, or geothermal power stations. More technological progress is achieved through the research mechanic, through which players may unlock new advancements like medicine, advanced weaponry, or mind-altering substances.

Players may be forced into several combative events. For example, during a pirate attack, the player will have to defend the colony by either drafting the characters or by building defensive mechanisms around the colony. Such defensive measures may include traps and automated turrets.

Characters in the game need constant nourishment. One of the challenges of a larger colony is finding a way to feed all the colonists. Players may combine hunting, farming, and animal husbandry to meet the colonist’s needs. Animals can be lured and tamed with food, but there is a small chance the animal will attack the tamer instead. Upon being tamed, domestic animals can reproduce.

On December 20, 2016, Alpha version 16 “Wanderlust” was released. Many new features were added regarding the world map, including: a spherical world map, time-zones, factions now starting with many bases, the ability to travel across the whole world map, the ability to set up multiple colonies, world generation, and customizable world map parameters. It is possible for players to attack other bases and plunder resources from them, angering the attacked faction in the process.

Players are able to install modifications (known as “mods”) distributed via the Steam Workshop, the game’s official forums, or other distribution sites