
BioWare decided to overhaul Kaidan's look to make him more memorable: in contrast to his generic outfit in previous games, Kaidan's default armor for 3 has a blue-and-white theme. BioWare opted to reuse Kaidan's visage from the first game and updated his face model for Mass Effect 3. Kaidan Alenko's face is modeled after Luciano Costa. He can also be romanced by a male Shepard in Mass Effect 3, where he would reveal his unrequited feelings for the Commander. Kaidan is a romance option for a female Shepard in the first game, and their relationship could persist over the entire trilogy depending on the player's choices. Kaidan shares the same overall story arc as Ashley in the sequels and while both characters effectively function as opposite-gender placeholders for one another throughout the trilogy, they start off differently in the first game and have distinct personalities and skills. The squad member who survives will afterwards serve as a constant reminder of the player's choices throughout the Mass Effect trilogy. In the first game the player has to decide whether Kaidan or Ashley Williams would survive during a late-game mission on the planet Virmire. Kaidan is cited as an example of the consequences that come with branching narratives in video games.

Kaidan suffers from infrequent, but debilitating, migraines as a side effect of the controversial L2 implants he was fitted with during his time at Biotic Acclimatization and Temperance Training ("BAaT"), nicknamed "brain camp" by Kaidan. In gameplay terms, Kaidan is a "Sentinel", who combines biotic and technological abilities to manipulate the environment, enhance defensive capabilities, disable and track enemies. Raised in Canada, Kaidan is a Systems Alliance officer born with the ability to manipulate dark energy, employ telekinesis and create mass effect fields called biotics, after his mother is affected by "Element Zero" during an incident in Singapore while he was in utero. Kaidan has received an overall mixed reception throughout his appearances in the Mass Effect trilogy. Initially presented as a heterosexual love interest for a female Shepard in the first game, the character is reintroduced in Mass Effect 3 as a bisexual love interest, a decision by BioWare which attracted mostly praise as well as some criticism.

In Mass Effect 3, Kaidan initially appears at the Alliance base in Vancouver before taking off on a mission to Mars with Shepard and the crew of the Normandy SR-2. If Kaidan survives the events of Mass Effect, by the events of Mass Effect 2 he is encountered on the human colony of Horizon after Shepard receives a tip that Horizon will be the next human colony to be abducted by the enigmatic race known as the Collectors.

Kaidan's fate on the planet Virmire is part of a pivotal decision which the player has to make in order to advance the narrative. The character is initially introduced in the original Mass Effect as a human Systems Alliance Officer and primary squad member in Commander Shepard's team. Kaidan Alenko is a fictional character in BioWare's Mass Effect franchise, who acts as a party member (or "squadmate") in the first and third games in the series. Kaidan's design in Mass Effect 3, as presented in The Art of the Mass Effect Universe
