[Here, University of Texas in Arlington grad student Joshua Wilson outlines the role enemy characters play in video games, and how they can be effectively implemented.]
At the heart of every game, there is interactivity.
Chris Crawford, a respected veteran in the field of game design, defined interactivity as "A cyclic process in which two active agents alternately (and metaphorically) listen, think, and speak." (Crawford 76). Interactivity is a conversation involving two agents that can gather information, process that information, and take action accordingly.
A goal is then applied to this conversation, creating a win/lose scenario. Coupling that scenario with a set of rules, in turn, fabricates a game to be played. Computers introduced a new active agent to the conversation, but interactivity is only as interactive as its least complex component. Operating systems and websites generally have a very low level of interactivity, because of the limited inputs and the absence of intelligence.
Artificial intelligence has the ability to learn and become infinitely complex and is often a term that is misused in the gaming industry. Games have enemies that challenge the player on a higher level of interactivity, but cannot learn anything new. These enemies have set commands to perform whenever a player interacts with them. There are many different aspects to enemies that need to be taken into account in order to generate an enjoyable challenge for the player.
While creating an enemy, the first characteristic to figure out is purpose. Enemies serve multiple purposes, but they always pertain to the discussion with the player. Enemies can be used to elicit an emotional response from the player. In most horror-themed games, the enemy's purpose is to cause fear by spooking the player or otherwisecreating a sense of dread.
There are a great many games that represent different aspects of the enemy developmental process. Resident Evil has been scaring players for years; if a monster doesn't serve the purpose of creeping out the players, then having it jump out suddenly is the next best option. Over the past few installments, the series has strayed into less scary and more action-based waters; disappointing the games' fanbase while also failing to reach out to its new target audience.
Drones of enemies can overwhelm and escalate tension during war simulation. A lack of enemies can build suspense or portray an allure of mystery. Shadow of the Colossus only has a limited number of boss-level opponents spread throughout a vast landscape. The journey the player takes is eerie, building tension before the eventual earth-rumbling awakening of each colossus.
Another aspect of purpose is to provide variety. A game made up of unchallenging enemies can become a bore; a game filled with challenging enemies can be too stressful. The Halo series prides itself on featuring a distinct hierarchy of alien soldiers and intense battles. Solo recon missions with scattered enemies transition into full-blown battles with raging armadas.
Creating a game of valleys (descending, weak enemies) and peaks (ascending, strong enemies) with varying quantities can provide a stimulating mixture for the player. With such a wide range of purpose, it is important to keep the player's safety in mind (Crawford 31-33). The player's accomplishments and progress should never be taken away from them. Saving is the main preserver of player achievements, and the placement of auto saves in correlation with challenging enemies can prevent this loss of safety to the player. So when creating an enemy, your first task is deciding its purpose and placing it in the hierarchy of challenge.