tower defense part of a series onstrategy video games subgenres 4x multiplayer online battle arena realtime strategy time management tower defense realtime tactics tactical roleplaying game turnbased strategy turnbased tactics artillery game wargame history chronology of 4x video games chronology of artillery video games chronology of grand strategy video games chronology of massively multiplayer online strategy video games chronology of multiplayer online battle arena video games chronology of realtime strategy video games chronology of realtime tactics video games chronology of tactical roleplaying video games chronology of turnbased strategy video games chronology of turnbased tactics video games more info portalstrategy games vte tower defense td is a subgenre of strategy video game where the goal is to defend a players territories or possessions by obstructing the enemy attackers usually achieved by placing defensive structures on or along their path of attack though many modern tower defense games include aspects of turnbased strategy strategic choice and positioning of defensive elements is an essential strategy of the genre ryan clements of ign attributes the popularity of such games to psychology and human vulnerability history precursors the tower defense genre can trace its lineage back to the golden age of arcade video games in the 1980s the object of the arcade game space invaders released in 1978 was to defend the players territory represented by the bottom of the screen against waves of incoming enemies the game featured shields which could be used to strategically to obstruct enemy attacks on the player and assist the player to defend their territory though not specifically to protect the territory the 1980 game missile command changed that by introducing a strategy element in the game players could obstruct incoming missiles and there were multiple attack paths in each attack wave while later arcade games like defender 1981 and choplifter 1982 lacked the strategy element of missile command they began a trend of games that shifted the primary objective to defending nonplayer items in these games defending nonplayers from waves of attackers is key to progressing parker brothers 1982 title star wars the empire strikes back for the atari 2600 was one of the first tieins to popularize the base defense style the concept of waves of enemies attacking the base in single file in this case atats proved a formula that was subsequently copied by many games as the shift from arcade to pc gaming began players were now able to choose from different methods of obstructing attackers progress green house a popular 1982 handheld game by nintendo nintendos popular 1980s game watch hand held games featured many popular precursors with their fixed sprite cells with binary states games with waves of attackers following fixed paths were able to make use of the technical limitations of the platform yet proved simple and enjoyable to casual gamers vermin 1980 one of the first had players with defending the garden a theme followed by many later games from relentless horde of moles the following years saw a flood of similar titles including manhole 1981 parachute 1981 and popeye 1981 1982 saw multiple titles with the primary object of protecting buildings from burning fire attack oil panic and mickey donald the later titles utilized multiple articulating screens to increase the difficulty for players with two screens these games introduced basic resource management eg oil and water forcing players to multitask green house 1982 was another popular two screen game in which players use clouds of pesticide spray to protect flowers from waves of attacking insects despite the early rush of archetypal titles ultimately there was a general decline in fixedcell games due to their the technical limitations simplistic gameplay and the rise of personal computers and handhelds the game boy correspondingly this genre also declined a rare exception was safebuster 1988 multiscreen in which the player protects a safe from a thief trying to blow it up by the mid 1980s the strategy elements began to further evolve early pc gaming examples include the 1984 commodore 64 titles gandalf the sorcerer a shooter with tower defense elements and imagine softwares 1984 release pedro pedro a garden defense game introduced new gameplay elements including different enemy types as well as the ability to place fixed obstructions and to build and repair the players territory modern genre emerges rampart released in 1990 is generally considered to have established the prototypical tower defense while rampart was popular similar games were rarely seen until the widespread adoption of the computer mouse on the pc the dos title ambush at sorinor 1993 was a rare exception from this era these titles would also bring roleplaying elements to the genre for the first time 20072008 boom between 2007 and 2008 the genre became a phenomenon due in part to the popularity of the tower defense mode in real time strategy games but mainly due to the rise of adobe flash independent developers as well as the emergence of major smartphone app stores from apple and google the first standalone browser games emerged in 2007 with the arrival of apples app store tower defense developers adapted quickly to the touchscreen interface and the titles were among the most downloaded many of them ported directly from flash among the more notable include bloons td 4 2009 which sold more than a million copies on ios the genres success also led to new releases on pc and video game consoles popular 2008 titles included pixeljunk monsters released in january defense grid the awakening a new breed of 3d games by the end of the boom most tower defense games were still stuck in the side scrolling isometric or topdown perspective graphical medium iron grip warlord released in november 2008 unsuccessfully pioneered the first person perspective shooter with the genre anomaly warzone earth released in 2011 introduced a variation of gameplay which has been described as reverse tower defense with the advent of social networking service applications such as the facebook platform tower defense has become a popular genre with titles such as bloons td and plants vs zombies adventures making the transition to turnbased play gameplay a screenshot of defenders of ardania showing the genres characteristic towers as well as units and a castle that serves as an end point the basic gameplay elements of tower defense are territories or possessions or collectively the base that must be defended by the player the base must survive waves of multiple incoming enemy attacks placement of tower elements or obstructions along the path of attacking enemies what differentiates tower defense from other base defending games such as space invaders is the players ability to strategically place or construct obstructions in the path of attacking enemies in tower defense unlike the base the players main character is usually but not always invincible as the primary object is the survival of the base rather than the player some features of modern tower defense player placed obstructions that can damage or kill enemy attackers before destroying the base ability to repair obstructions ability to upgrade obstructions some sort of currency with which to purchase upgrades and repairs this can be time in game currency or experience points such as being earned by the defeat of an attacking unit enemies capable of traversing multiple paths each wave usually has a set number and types of enemies many modern tower defense games evolved from realtime to turn based gameplay in which there is a cycle including distinct phases such as build defend and repair many games such as flash element tower defense feature enemies that run through a maze which allows the player to strategically place towers for optimal effectiveness some versions are a hybrid of these two types with preset paths that can be modified to some extent by tower placement or towers that can be modified by path placement often an essential strategy is mazing which is the tactic of creating a long winding path of towers to lengthen the distance the enemies must traverse to get past the defense sometimes juggling is possible by alternating between barricading an exit on one side and then the other side to cause the enemies to path back and forth until they are defeated some games also allow players to modify the attack strategy used by towers to be able to defend for an even more reasonable price the degree of the players control or lack thereof in such games also varies from games where the player controls a unit within the game world to games where the player has no direct control over units at all it is a common theme in tower defense games to have air units which do not pass through the layout of the maze but rather fly over the towers directly to the end destination some tower defense games or custom maps also require the player to send out enemies to their opponents game boards respectively their controlled areas at a common game board such games are also known as tower wars games uspto trademark on june 3 2008 com2us corporation was awarded the trademark for the term tower defense filed on june 13 2007 serial number 3442002 the corporation is reported to have started enforcing the trademark in early 2010 developers of games on apples app store reported receiving messages requiring name changes for their games citing trademark violation adding the phrase tower defense in capital letters to the description of an app submission to itunesconnect and the app store automatically triggers a warning that the submission is likely to be rejected for use of the term however writing the phrase in lower case is still acceptable as tower defense is a valid description of a game style vtevideo game genres listaction beat em up hack and slash fighting maze pacman clone platform shooter firstperson thirdperson light gun shoot em up tactical survival battle royale actionadventure grand theft auto clone immersive sim metroidvania stealth survival horror psychological horror adventure escape the room interactive fiction interactive movie visual novel mmo mmofps mmorpg mmorts mud roleplaying action roleplaying dungeon crawl roguelike tactical roleplaying simulation construction and management business city government life simulation dating sim digital pet god social simulation sports strategy 4x multiplayer online battle arena realtime strategy tower defense time management realtime tactics turnbased strategy turnbased tactics wargame vehicle simulation flight simulator amateur combat space racing kart racing sim racing submarine simulator train simulator vehicular combat other genres artillery breakout clone digital collectible card game eroge exergame incremental music rhythm nongame party programming puzzle sokoban tilematching related concepts aaa game advertising arcade game art game audio game casual game christian game crossover game educational game fmv gamification indie game multiplayer video game nonlinear gameplay open world nonviolent video game online game browser game multiplayer online game online gambling socialnetwork game pervasive game serious game toystolife twitch gameplay video game clone 