The futuristic plot starts off revolving around three characters who are stranded on a planet located in the frontiers of known space, where their space liner crashed. 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. They can either choose to join, or they can be taken prisoner and talked into joining the colony during their confinement. 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. However, players are given the choice to continue to play, as it's possible to wait for a wanderer to take up residence in the ruins of the colony and continue the game.
Gameplay
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.
During the set-up of a game-round, the backstory, medical conditions, capabilities and certain personality traits of the characters are randomly generated, but players may opt to re-randomize those traits indefinitely. 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 suggests three preconfigured AI storytellers, all of which have changeable difficulty settings:
Cassandra Classic steadily increases the difficulty of the game by increasing the difficulty of negative events as the time passes.
Phoebe Chillax gives large periods of peace between negative events, but these are still challenging to the player if set on a high difficulty.
Randy Random provides gameplay with unpredictable events occurring at random intervals. The level and frequency of negative events are randomly generated and can occur at any time.
Events can be good, neutral or bad. When choosing a story teller the player also chooses what save mode and difficulty to play on. There are 6 different difficulties ranging from peaceful to merciless. These influence the severity and frequency of events as well as the good, neutral, bad balance of events. The game also has two modes for saving the game that needs to be chosen. One mode, called commitment mode, only lets the player save and exit the game making the choices made for each random event permanent. The other mode allows saving and loading anytime during the game allowing the player to experience multiple ways to respond to the event given.
Characters
Management of each character's psyche is a crucial aspect of gameplay. 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 broken 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, as 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 deciding to carry and store items.
Technological progress
Another large aspect of game-play is technological progression. Early on players may harness electricity, which unlocks a plethora of machines and increases the colony's efficiency. However, players are then 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. By devoting time and personnel to research, players may unlock new advancements like medicine, advanced weaponry, or mind-altering substances.
Combat
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.
Starvation
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. Eleven animals were added including elephants, two breeds of dog, cows, chickens, boomrats, and others. Reproduction, a feature that was highly requested by players, was also added, allowing the player much more freedom in managing their animal populations.
Colonization
On December 20, 2016, Alpha version 16 "Wanderlust" was released. Many new features were added regarding the world map; these included: changing the world to be spherical, time-zones, factions now starting with many bases, the ability to travel the world, the ability to set up multiple colonies, world generation, and world generation parameters. It is possible for players to attack other bases and plunder resources from them, angering the attacked faction in the process.
Modifications
Players are able to install modifications distributed via the Steam Workshop, the games official forums, or other distribution sites.
Reception
The game has been favourably compared to other difficult management-survival games such as Dwarf Fortress.
Accolades
In 2016 RimWorld was voted Indie DB's "indie of the year". In 2018 Rimworld was voted Steam's Top User-Rated Game, from all categories. The game was nominated in 2019 for the category of "Strategy/Simulation Game of the Year" at the 22nd D.I.C.E. Awards.
Development
On February 24, 2020 the first DLC, Royalty, was released with the 1.1 update.
