Ryan Clements of IGN attributes the popularity of such games to psychology and human vulnerability. The tower defense genre can trace its lineage back to the golden age how to hack adobe flash player games arcade video games in the 1980s. Missile Command, they began a trend of games that shifted the primary objective to defending non-player items.
In these games, defending non-players from waves of attackers is key to progressing. 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. 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 Software’s 1984 release Pedro. Rampart, released in 1990 is generally considered to have established the prototypical tower defense. Rampart introduced player placed defenses that automatically attack incoming enemies.
In addition, it has distinct phases of build, defend and repair. While Rampart was popular, similar games were rarely seen until the widespread adoption of the computer mouse on the PC. With the arrival of Apple’s 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. The genre’s success also led to new releases on PC and video game consoles. By the end of the boom, most tower defense games were still stuck in the side scrolling, isometric, or top-down 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”, “tower attack”, and “tower offense”.
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 turn-based play. In Tower defense, unlike the base, the player’s main character is usually, but not always, and certainly not never, invincible, as the primary object is the survival of the base rather than the player. Many modern tower defense games evolved from real-time to turn-based gameplay in which there is a cycle in which there are distinct phases such as build, defend, repair, and celebrate. Many games, such as Flash Element Tower Defense feature enemies that scamper through a “maze”, which allows the player to strategically place “towers” for optimal effectiveness. 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.