Roguelike

Roguelike is a style of role-playing game traditionally characterized by a dungeon crawl through procedurally generated levels, turn-based gameplay, grid-based movement, and permanent death of the player character. Most roguelikes are based on a high fantasy narrative, reflecting the influence of tabletop role-playing games such as Dungeons & Dragons.
Though Beneath Apple Manor predates it, the 1980 game Rogue, which is an ASCII-based game that runs in terminal or terminal emulator, is considered the forerunner and the namesake of the genre, with derivative games mirroring Rogues character- or sprite-based graphics. These games were popularized among college students and computer programmers of the 1980s and 1990s, leading to hundreds of variants. Some of the better-known variants include Hack, NetHack, Ancient Domains of Mystery, Moria, Angband, Tales of Maj'Eyal, and Dungeon Crawl Stone Soup. The Japanese series of Mystery Dungeon games by Chunsoft, inspired by Rogue, also fall within the concept of roguelike games.
The exact definition of a roguelike game remains a point of debate in the video game community. A "Berlin Interpretation" drafted in 2008 defined a number of high- and low-value factors of "canon" roguelike games Rogue, NetHack and Angband, which have since been used to distinguish these roguelike games from edge cases like Diablo. Since then, with more powerful home computers and gaming systems and the rapid growth of indie video game development, several new "roguelikes" have appeared, with some but not all of these high-value factors, nominally the use of procedural generation and permadeath, while often incorporating other gameplay genres, thematic elements, and graphical styles; common examples of these include Spelunky, FTL: Faster Than Light, The Binding of Isaac, Slay the Spire, Crypt of the NecroDancer, and Hades. To distinguish these from traditional roguelikes, such games may be referred to as roguelite or roguelike-like. Despite this alternative naming suggestion, these games are often referred to as roguelike and use the roguelike tag on various marketplaces such as Steam.

Origin

The term "roguelike" came from Usenet newsgroups around 1993, as this was the principal channel the players of roguelike games of that period were using to discuss these games, as well as what the developers used to announce new releases and even distribute the game's source code in some cases. With several individual groups for each game, it was suggested that with rising popularity of Rogue, Hack, Moria, and Angband, all of which shared common elements, that the groups be consolidated under an umbrella term to facilitate cross-game discussion. Debate among users of these groups ensued to try to find an encapsulating term that described the common elements, starting with rec.games.dungeon.*, but after three weeks of discussion, rec.games.roguelike.*, based on Rogue, which was at the time considered to be the oldest of these types of games, was picked as "the least of all available evils". By the time it was suggested that a group be created to discuss the development of these kind of games in 1998, the "roguelike" term was already established within the community. This usage parallels that of "Doom clone", a term used in the 1990s that later evolved into the more generic "first-person shooter".

Gameplay and design

Drawing from the concepts of tabletop role-playing games such as Dungeons & Dragons, nearly all roguelikes give the player control of a character, which they may customize by selecting a class, race, and gender, and adjusting attributes points and skills. At the start of the game, the character is placed at the top-most level of a dungeon, with basic equipment such as a simple weapon, armor, torches, and food. Following along the role-playing concept of a dungeon crawl, the player moves the character through the dungeon, collecting treasure which can include new weapons, armours, magical devices, potions, scrolls, food, and money, while having to fight monsters that roam the dungeon. Most combat is performed simply by attempting to move the character into the same space as the monster. The game then calculates the damage that the character and monster deal. Other types of attacks, such as firing an arrow or performing an offensive magic spell, can often be performed as well.
Defeating monsters earns the character experience points, and after earning enough points, the character will gain an experience level, improving their hit points, magic capability, and other attributes. Monsters may drop treasure to be looted. The character dies if they lose all their hit points. As most roguelikes feature the concept of permadeath, this represents the end of the game, and the player will need to restart the game with a newly made character. Roguelikes are nearly always turn-based, with the game only reacting when the player makes an action with the character. This allows players to evaluate a difficult situation, such as being cornered by several monsters, at their own pace and determine the best strategy.
The player generally has to explore the dungeon to reveal its contents, similar to a fog of war. Many roguelikes include visibility elements, such as a torch to provide illumination to see monsters in nearby squares, or line of sight to limit which monsters are visible from the player's position. Dungeons tend to be connected by stairs; lower dungeon levels generally are more difficult than higher ones, so that an underdeveloped character will have difficulty progressing too fast. Dungeon levels and the population of monsters and treasure within them are generated randomly using procedural generation, so no game is the same on subsequent playthroughs. Most roguelikes have an ultimate goal of either claiming an item located at the deepest level of the dungeon, or defeating a specific monster that lives on that level. Typical roguelikes assess the player's performance at the end of the game through a score based on the amount of treasure, money, experience earned, and how fast the player finished the game, if they managed to do so. The score is displayed in a ranked scoreboard to compare the player's performance on successive runs.

Key features

What gameplay elements explicitly define a "roguelike" game remains a point of debate within the video game community. There is broad agreement that roguelike games incorporate gameplay elements popularized by the text-based game Rogue, which bore out many variations due to its success; As of 2015, several hundred games claiming to be roguelikes were available through the Steam game catalog, and the user-run wiki RogueBasin tracks hundreds of roguelikes and their development.
Some players and developers sought a more narrow definition for "roguelike" as variations on Rogue introduced new concepts or eschewed other principles that they felt moved the games away from the flavor of what Rogue was. At the International Roguelike Development Conference 2008 held in Berlin, Germany, players and developers established a definition for roguelikes known as the "Berlin Interpretation". The Berlin Interpretation set out a set of high-value and low-value factors, basing these lists on five canon roguelike games: ADOM, Angband, Linley's Dungeon Crawl, NetHack, and Rogue. The Interpretation was designed to determine "how roguelike a game is", noting that missing a factor does not eliminate a game from being a roguelike, nor does possessing the features make a game roguelike. John Harris of Game Set Watch exemplified this by using these criteria to numerically score some seemingly roguelike games; Linley's Dungeon Crawl and NetHack scored highest, earning 57.5 points of 60 available based on the Interpretation, while Toe Jam & Earl and Diablo, games commonly compared to roguelikes, earned only about half of the points.
The Berlin Interpretation defined nine high-value factors:

The game uses random dungeon generation to increase replayability. Games may include pre-determined levels such as a town level common to the Moria family where the player can buy and sell equipment, but these are considered to reduce the randomness set by the Berlin Interpretation. This "random generation" is nearly always based on some procedural generation approach rather than true randomness. Procedural generation uses a set of rules defined by the game developers to seed the generation of the dungeon generally to assure that each level of the dungeon can be completed by the player without special equipment, and also can generate more aesthetically pleasing levels. In addition, the appearances of magical items may vary from run to run. For example, a "bubbly" potion might heal wounds one game, then poison the player character in the next.
The game uses permadeath. Once a character dies, the player must begin a new game, known as a "run", which will regenerate the game's levels anew due to procedural generation. A "save game" feature will only provide suspension of gameplay and not a limitlessly recoverable state; the stored session is deleted upon resumption or character death. Players can circumvent this by backing up stored game data, an act that is usually considered cheating; the developers of Rogue introduced the permadeath feature after introducing a save function, finding that players were repeatedly loading saved games to achieve the best results. According to Rogues Michael Toy, they saw their approach to permadeath not as a means to make the game painful or difficult but to put weight on every decision the player made as to create a more immersive experience.
The game is turn-based, giving the player as much time as needed to make a decision. Gameplay is usually step-based, where player actions are performed serially and take a variable measure of in-game time to complete. Game processes advance based on the passage of time dictated by these actions.
The game is grid-based. Gameplay takes place on a uniform grid of tiles. This is usually presented in an ASCII representation of the dungeon.
The game is non-modal, in that every action should be available to the player regardless of where they are in the game. The Interpretation notes that shops like in Angband do break this non-modality.
The game has a degree of complexity due to the number of different game systems in place that allow the player to complete certain goals in multiple ways, creating emergent gameplay. For example, to get through a locked door, the player may attempt to pick the lock, kick it down, burn down the door, or even tunnel around it, depending on their current situation and inventory. A common phrase associated with NetHack is "The Dev Team Thinks of Everything" in that the developers seem to have anticipated every possible combination of actions that a player may attempt to try in their gameplay strategy, such as using gloves to protect one's character while wielding the corpse of a cockatrice as a weapon to petrify enemies by its touch.
The player must use resource management to survive. Items that help sustain the player, such as food and healing items, are in limited supply, and the player must figure out how to use these most advantageously to survive in the dungeon. USGamer further considers "stamina decay" as another feature related to resource management. The player's character constantly needs to find food to avoid starvation, which prevents the player from exploiting health regeneration by simply either passing turns for a long period of time or fighting very weak monsters at low level dungeons. Rich Carlson, one of the creators of an early roguelike-like Strange Adventures in Infinite Space, called this aspect a sort of "clock", imposing some type of deadline or limitation on how much the player can explore and creating tension in the game.
The game is focused on hack and slash-based gameplay, where the goal is to kill many monsters, and where other peaceful options do not exist.
The game requires the player to explore the world, and discover the purpose of unidentified items. In games featuring random generation, this must be done again every playthrough, as both the map and the appearances of items change.

Low-value factors from the Berlin Interpretation are:

The game is based on controlling only a single character throughout one playthrough.
Monsters have behavior that is similar to the player-character, such as the ability to pick up items and use them, or cast spells.
The game aimed to provide a tactical challenge that may require players to play through several times to learn the appropriate tactics for survival.
The game involves exploring dungeons which are made up of rooms and interconnecting corridors. Some games may have open areas or natural features, such as rivers, though these are considered against the Berlin Interpretation.
The game presents the status of the player and the game through numbers on the game's screen/interface.

Though this is not addressed by the Berlin Interpretation, roguelikes are generally single-player games. On multi-user systems, leaderboards are often shared between players. Some roguelikes allow traces of former player characters to appear in later game sessions in the form of ghosts or grave markings. Some games such as NetHack even have the player's former characters reappear as enemies within the dungeon. Multi-player turn-based derivatives such as TomeNET, MAngband, and Crossfire do exist and are playable online.