Real-time strategy

Real-time strategy (RTS) is a sub-genre of strategy video game which do not progress incrementally in turns. Brett Sperry is credited with coining the term to market Dune II.

In an RTS, as in other wargames, the participants position and maneuver units and structures under their control to secure areas of the map and/or destroy their opponents' assets. In a typical RTS it is possible to create additional units and structures during the course of a game. This is generally limited by a requirement to expend accumulated resources. These resources are in turn garnered by controlling special points on the map and/or possessing certain types of units and structures devoted to this purpose. More specifically, the typical game of the RTS genre features resource gathering, base building, in-game technological development and indirect control of units.

The tasks a player must perform to succeed at an RTS can be very demanding, and complex user interfaces have evolved to cope with the challenge. Some features have been borrowed from desktop environments, most prominently the technique of "clicking and dragging" to select all units under a given area.

Though some game genres share conceptual and gameplay similarities with the RTS template, recognized genres are generally not subsumed as RTS games. For instance, city-building games, construction and management simulations, and games of the real-time tactics variety are generally not considered to be "real-time strategy".

Precursors and early Genesis
The genre that is recognized today as "real-time strategy" emerged as a result of an extended period of evolution and refinement. Games that are today sometimes perceived as ancestors of the real-time strategy genre were never marketed or designed as such at the original date of publication. As a result, designating "early real-time strategy" titles is problematic because such games are being held up to modern standards. The genre initially evolved separately in the UK and North America, afterward gradually merging into a unified worldwide tradition.

In the UK, the genre's beginning can be traced to Stonkers by John Gibson, published in 1983 by Imagine Software for the ZX Spectrum, and Nether Earth published on ZX Spectrum in 1987. In North America, the oldest game retrospectively classified as real-time strategy by many sources is Rescue Raiders (1984), designed by Sir-Tech. It was followed by The Ancient Art of War at Sea in 1987, although Dani Bunten Berry's (of M.U.L.E fame) Cytron Masters (1982), developed by Ozark Softscape and released by SSI, also has been considered the earliest game of the genre.

Some writers list Intellivision's Utopia by Don Daglow (1982) as the first real-time strategy game. In Utopia two players build resources and carry out combat by proxy. It contains the direct-manipulation tactical combat now common in that the players can assume direct control over a PT boat and sink the opponents fishing boats. Another early example from the same year is Legionnaire on the Atari 8-bit family, written by Chris Crawford for Avalon Hill. This was effectively the opposite of Utopia, in that it offered a complete real-time tactical combat system with variable terrain and mutual-help concepts, but lacked any resource collection and economy/production concepts. As a result, this game might be better considered an early forerunner of the RTT (real-time tactics) genre.

Herzog Zwei for the Sega Genesis in 1989 is the earliest example of a game with a feature set that falls under the contemporary definition of modern RTS. In Herzog Zwei, though you only control one unit, the manner of control foreshadowed the point-and-click mechanic of later games. Also, control and destruction of bases was an important aspect of the game, as were the economic/production aspects of those bases.

Notable as well are early games like Mega Lo Mania by Sensible Software (1991) and Supremacy (also called Overlord - 1990). Although these two lacked direct control of military units, they both offered considerable control of resource management and economic systems. In addition, Mega Lo Mania has advanced technology trees that determine offensive and defensive prowess. Another early (1988) game, Carrier Command by Realtime Games, involved real-time responses to events in the game, requiring management of resources and control of vehicles. The early game Sim Ant by Maxis (1991) had resource gathering, and controlling an attacking army by having them follow a lead unit. However, it was with the release of Dune II from Westwood Studios (1992) that real-time strategy became recognized as a distinct genre of video games.

1992–1998: seminal titles
Although real-time strategy games have an extensive history, some titles have served to define the popular perception of the genre and expectations of real-time strategy titles more than others, in particular the games released between 1992 and 1998 by Westwood Studios and Blizzard Entertainment.

Westwood's Dune II: The Building of a Dynasty (1992) introduced all the core concepts and mechanics of modern real-time strategy games that are still used today, such as using the mouse to move units, and gathering resources, and as such served as prototype for later real-time strategy games.

The success of Dune II encouraged several games which became influential in their own right. Warcraft: Orcs & Humans (1994) achieved great prominence upon its release, owing in part to its use of a fantasy setting and also to its depiction of a wide variety of buildings (such as farms) which approximated a full fictitious society, not just a military force. Command & Conquer became the first popular RTS game to utilize competitive multiplayer. Command & Conquer, as well as Command and Conquer: Red Alert, became the most popular early RTS games. These two games contended with Warcraft II: Tides of Darkness after its release in late 1995.

Total Annihilation, released by Cavedog Entertainment in 1997, introduced 3D units and terrain and focused on huge battles that emphasized macromanagement over micromanagement. It featured a streamlined interface that would influence many RTS games in later years. Age of Empires, released by Ensemble Studios in 1997 try to put a game in a more slow pace, combining elements of Civilization with the real-time strategy concept by introducing ages of technologies. In 1998, Blizzard Entertainment released the game StarCraft, which became an international phenomenon and is still played in large professional leagues to this day. Collectively, all of these games defined the genre, providing the de facto benchmark against which new real-time strategy games are measured.

Refinement and transition to 3D
The real-time strategy genre has been relatively stable since 1995. Additions to the genre's concept in newer games tend to emphasize more of the basic RTS elements (higher unit caps, more unit types, larger maps, etc.). Rather than innovations to the game concept, new games generally focus on refining aspects of successful predecessors. As the paragon example of gameplay refinement, Cavedog Entertainment's acclaimed Total Annihilation from 1997 distilled the core mechanics of Command & Conquer, and introduced the first 3D units and terrain in real-time strategy games. The Age of Empires idea was refined further by Stainless Steel Studios' Empire Earth in 2001. GSC Game World's Cossacks: European Wars series took the genre in a different direction, bringing population caps into the tens of thousands.

Populous: The Beginning (1998), Jeff Wayne's The War of the Worlds (1998) and Homeworld (1999) were among the first completely 3D real-time strategy titles. Homeworld was notable in that it featured a 3d environment in space, therefore allowing movement in every direction, a feature which its semi-sequel, Homeworld Cataclysm (2000) continued to build upon adding features such as waypoints. Homeworld 2, released in 2003, streamlined movement in the 360° 3D environment. Furthermore, Machines, which was also released in 1999 and featured a nearly 100% 3D environment, attempted to combine the RTS genre with FPS although it was not a particularly successful title. These games were followed by a short period of interest in experimental strategy games such as Allegiance (2000).

It is only in approximately 2002 that 3D real-time strategy became the standard, with both Warcraft III (2002) and Ensemble Studio's Age of Mythology (2002) being built on a full 3D game engine. Kohan: Immortal Sovereigns introduced classic wargame elements, such as supply lines to the genre. Battle Realms (2001) was another full 3D game, but had limited camera views.

The move from 2D to 3D has been criticized in some cases. Issues with controlling the camera and placement of objects have been cited as problems.

Relatively few genres have emerged from or in competition with real-time strategy games, although Real-time tactics, a superficially similar genre, emerged around 1995. In 1998, Activision attempted to combine the real-time strategy and first-person shooter genres in Battlezone, while in 2002 Rage Games Limited attempted this with the Hostile Waters games, and Natural Selection, a game modification based on the Half-Life engine. Savage: The Battle for Newerth combined the RPG and RTS elements in an online game. In 2010, StarCraft II, a sequel to the hit StarCraft was released on a full 3D engine. With improved graphics from the original. StarCraft II was praised for its intense detail for both rendered and gameplay. StarCraft II also supports NVIDIA's 3D Vision on the launch of Patch 1.1.

Specialization and evolution
A few games have experimented with diversifying map design, which continues to be largely two-dimensional even in 3D engines. Earth 2150 allowed units to tunnel underground, effectively creating a dual-layer map; three-layer (orbit-surface-underground) maps were introduced in Metal Fatigue. In addition, units could even be transported to entirely separate maps, with each map having its own window in the user interface. Three Kingdoms: Fate of the Dragon (2001) offered a simpler model: the main map contains locations that expand into their own maps. In these examples, however, gameplay was essentially identical regardless of the map layer in question. Dragonshard (2005) emphasized its dual-layer maps by placing one of the game's two main resources in each map, making exploration and control of both maps fundamentally valuable.

Some games, borrowing from the real-time tactics (RTT) template, have moved toward an increased focus on tactics and a de-emphasis on resource management, with titles such as Warhammer 40,000: Dawn of War (2004), Star Wars: Empire at War (2006), and Company of Heroes (2006) replacing the traditional resource gathering model, where designated resource gathering units collect the resources used for producing further units or buildings, with a strategic control-point system, where control over strategic points progressively yields construction/reinforcement points. Ground Control was the first such game to replace individual units with "squads".

Others are moving away from the traditional real-time strategy game model with the addition of other genre elements. An example is Sins of a Solar Empire, released by Ironclad Games, which mixes elements of grand-scale stellar empire building games like Master of Orion with real-time strategy elements.

Gameplay
In a typical real-time strategy game, the screen is divided into a map area displaying the game world and terrain, units, and buildings, and an interface overlay containing command and production controls and often a "radar" or "minimap" overview of the entire map. The player is usually given an isometric perspective of the world, or a free-roaming camera from an aerial viewpoint for modern 3D games. The primary form of input is the mouse, with which commands are given and the map is scrolled, and which is generally accompanied by keyboard shortcuts.

In most Real Time Strategy games, especially the earliest ones, the gameplay is generally fast-paced and requires very quick reflexes. For this reason, and the amount of violence in some games makes RTS games close to action games in terms of gameplay.

Gameplay generally consists of the player being positioned somewhere in the map with a few units or a building that is capable of building other units/buildings. Often, but not always, the player must build specific structures to unlock more advanced units in the tech tree. However, all RTS games require the player to build an army (ranging from small squads of no more than 2 units, to literally hundreds of units) and using them to either defend themselves from a virtual form of Human wave attack or to eliminate enemies who possess bases with unit production capacities of their own.

Resource gathering is commonly the main focus of the RTS games, but other titles of the genre place higher gameplay significance to the how units are used in combat, the extreme example of which are games of the real-time tactical genre. Some titles impose a ceiling on the number simultaneous troops, which becomes a key gameplay consideration, a significant example being StarCraft, while other titles have no such unit cap.

Micromanagement and macromanagement
Micromanagement refers to when a player's attention is directed more toward the management and maintenance of his or her own individual units and resources. This creates an atmosphere in which the interaction of the player is constantly needed. On the other hand, macromanagement refers to when a player's focus is directed more toward economic development and large-scale strategic maneuvering, allowing time to think and consider possible solutions. Micromanagement frequently involves the use of combat tactics.

Criticism of gameplay
Because of their generally faster-paced nature (and in some cases a smaller learning curve), real-time strategy games have surpassed the popularity of turn-based strategy computer games. In the past, a common criticism was to regard real-time strategy games as "cheap imitations" of turn-based strategy games, arguing that real-time strategy games had a tendency to devolve into "click-fests"  in which the player who was faster with the mouse generally won, because they could give orders to their units at a faster rate. The common retort is that success involves not just fast clicking but also the ability to make sound decisions under time pressure. The "clickfest" argument is also often voiced alongside a "button babysitting" criticism, which pointed out that a great deal of game time is spent either waiting and watching for the next time a production button could be clicked, or rapidly alternating between different units and buildings, clicking their respective button.

A third common criticism is that real-time gameplay often degenerates into "rushes" where the players take turns throwing swarms of units at each other. For example, the original Command & Conquer gave birth to the now-common "tank rush" tactic, where the game outcome is often decided very early on by one player gaining an initial advantage in resources and producing large amounts of a relatively powerful but still quite cheap unit&mdash;which is thrown at the opposition before they have had time to establish defenses or production. Although this strategy has been criticized for encouraging overwhelming force over strategy and tactics, defenders of the strategy argue that they're simply taking advantage of the strategies utilized, and some argue that it's a realistic representation of warfare. One of the most infamous versions of a rush is the "Zergling rush" from the real-time strategy game StarCraft; in fact, the term "zerging" has become synonymous with rushing.

A fourth criticism of the RTS genre is the importance of skill over strategy in real-time strategy games. The manual dexterity and ability to multitask and divide one's attention is often considered the most important aspect to succeeding at the RTS genre. According to Troy Dunniway, former Westwood developer who has also worked on Command and Conquer 3: Tiberium Wars, "A player controls hundreds of units, dozens of buildings and many different events that are all happening simultaneously. There is only one player, and he can only pay attention to one thing at a time. Expert players can quickly flip between many different tasks, while casual gamers have more problems with this."

Tactics vs. strategy
Real-time strategy games have been criticized for an overabundance of tactical considerations when compared to the amount of strategic gameplay found in such games. According to Chris Taylor, lead designer of Supreme Commander, "[My first attempt at visualizing RTSs in a fresh and interesting new way] was my realizing that although we call this genre 'Real-Time Strategy,' it should have been called 'Real-Time Tactics' with a dash of strategy thrown in." (Taylor then posits his own game as having surpassed this mold by including additional elements of broader strategic scope.)

In general terms, military strategy refers to the use of a broad arsenal of weapons including diplomatic, informational, military, and economic resources, whereas military tactics is more concerned with short-term goals such as winning an individual battle. In the context of strategy video games, however, the difference is often reduced to the more limited criteria of either a presence or absence of base building and unit production.

In an article for Gamasutra, Nathan Toronto criticizes real-time strategy games for too often having only one valid means of victory &mdash; attrition &mdash; comparing them unfavorably to real-time tactics games. Players' awareness that the only way for them to win or lose is militarily makes them unlikely to respond to gestures of diplomacy. The result is that the winner of a real-time strategy game is too often the best tactician rather than the best strategist. Troy Goodfellow counters this by saying that the problem is not that real-time strategy games are lacking in strategy (he says attrition is a form of strategy), rather it is that they too often have the same strategy: produce faster than you consume. He also states that building and managing armies is the conventional definition of real-time strategy, and that it is unfair to make comparisons with other genres.

In an article for Gamespy, Mark Walker criticizes real-time strategy games for their lack of combat tactics, suggesting real-time tactics games as a more suitable substitute. He also says that developers need to begin looking outside the genre for new ideas in order for strategy games to continue to be successful in the future.

Turn-based vs. real-time
A debate has emerged between fans of real-time strategy and turn-based strategy (and related genres) based on the merits of the real-time and turn-based systems. Some titles attempt to merge the two systems: for example, the role-playing game Fallout uses turn-based combat and real-time gameplay, while the real-time strategy games Homeworld, Rise of Nations and the games of the Total War series allow the player to pause the game and issue orders. Additionally, the Total War series has a combination of a turn-based strategy map with a real-time battle map.

Real-time strategy games on the consoles
Real-time strategy games made for video game consoles have been consistently criticized due to their control schemes. The PC's keyboard and mouse are generally considered to be superior to a console's gamepad. This is similar to the main criticism of console based First Person Shooter games, a mouse guarantees a higher level of pointer accuracy than a gamepad can offer. RTS games for the consoles have generally met with mixed success. However Halo Wars, released in 2009 for the Xbox 360, garnered generally positive reviews, achieving an 82% critic average on aggregate web sites, and sold over 1 million copies. MetaCritic and Game Rankings. Although, according to IGN, the gameplay lacks the traditional RTS concepts of limited resources and resource gathering, and multiple buildings.

Graphics
Total Annihilation (1997) was the first real-time strategy game to utilize true 3D units, terrain, and physics in both rendering and in game-play. For instance, missiles in Total Annihilation travel in real-time in simulated 3D space, and can miss their target by passing over or under it. Similarly, missile-armed units in Earth 2150 are at a serious disadvantage when the opponent is on high ground, as the missiles often hit the cliffside, even in the case when the attacker is a missile-armed helicopter. Homeworld and Warzone 2100 (both released in 1999) advanced the use of fully 3D environments in real-time strategy titles. In the case of Homeworld, the game is set in space, offering a uniquely exploitable 3D environment in which all units can move vertically in addition to the horizontal plane. However, the near-industry-wide switch to full 3D was very gradual and most real-time strategy titles, including the first sequels to Command & Conquer, initially used isometric 3D graphics made by pre-rendered 3D tiles. Only in later years did these games begin to use true 3D graphics and game-play, making it possible to rotate the view of the battlefield in real-time. Spring is a good example of the transformation from semi-3D to full-3D game simulations. It's an open-source project aiming to give a Total Annihilation gameplay experience in 3 dimentions.

Recently, real-time strategy games have more commonly incorporated physics engines, such as Havok, in order to increase realism experienced in gameplay. A modern real-time strategy game that uses a physics engine is Ensemble Studios' Age of Empires III, released on October 18, 2005, which used the Havok Game Dynamics SDK to power its real-time physics. Company of Heroes is another real-time strategy game that uses realistically modeled physics as a part of gameplay, including fully-destructible environments.