Within the series' narrative, Mordin helped create and distribute measures to strengthen an artificial population control plague, named the Genophage, used against the krogan, a fast-breeding warlike alien race.

His goal is to develop a cure for the Genophage in response to the galaxy-wide invasion by the antagonistic Reapers and intends to distribute it in the atmosphere of Tuchanka, the krogan homeworld.

At one point in the second game, Mordin sings an alternate version of Gilbert and Sullivan's Major-General's Song; numerous critics considered it one of the trilogy's best moments.

[3] David Kates, creator of his musical theme, believed him to add a little comic relief to the game, calling him "quirky, a little bit disorganized, definitely cerebral, overthinking".

Despite holding some regrets over doing so, working on the Genophage proved intellectually challenging, and he believes if he hadn't done it, someone less skilled might have—risking completely sterilizing the krogan by accident.

", and to that end one piece of concept art directly took features from a picture of Eastwood and incorporated them on a salarian, leading to Mordin's aged look.

Due to his relative old age, Mordin allowed the developers to explore the later lifestages of the Mass Effect universe's aliens.

[13] Writer Brian Kindregan explained in an interview that planned content is usually cut due to time and financial considerations: in this instance, the team had already developed two major confrontation scenes between other squadmates, which may complicate the player's preparations for the suicide mission due to the potentially irreparable loss of a squadmate’s loyalty.

[6] This structure also led to stylistic choices with their clothing, under the idea that they'd stuff fabric there after meeting other races, which art director Matt Rhodes compared to "a bald man wearing a toupée".

[6] Mordin's design specifically tried to balance his scientific side and his ability as a combat-ready tech specialist due to time in the salarian special forces.

[6] The missing horn is given alternate in-universe explanations in the second game's Lair of the Shadow Broker downloadable content pack and in the Mass Effect: Foundation comic series.

Commander Shepard, the player character and protagonist of the game, goes to Omega to recruit him as a tech specialist for an assault on the Collector base.

During the mission, which takes place in a hospital, Mordin discovers horrific tests by krogan trying to cure the Genophage, and the player may have Shepard confront him about his work on it.

Eventually, Mordin finds Maelon, who is revealed to have voluntarily joined the krogan due to guilt over helping develop the Genophage.

Mordin then discovers Maelon has found valuable data that could prove useful to curing the Genophage, and the player can choose whether to destroy it or save it.

As a scientist, Mordin uses technology abilities in battle, particularly Incinerate and Cryo Blast, which respectively tear through armor and snap freeze enemies.

However, as he is just a scientist, he is the weakest of all the squad members, with the game's algorithm written to kill Mordin first during the suicide mission's final act should the team's defensive capabilities not be strong enough.

If a save is imported where Mordin died during the Suicide Mission, his role in the game will be replaced by another salarian named Padok Wiks.

The ninth issue of the Foundation comic series, published March 2014, focuses on Mordin's creation of the modified Genophage prior to the games' events.

Mordin researches and develops the new Genophage strain in less than a week, and a month later he and other STG members go to Tuchanka to test it on a krogan colony.

[23] Dark Horse released a set of Mass Effect playing cards, featuring Mordin as the King of Diamonds and other characters in other roles.

1UP.com's Jose Otero wrote an article dedicated to why Mordin was "awesome", saying he "epitomize[d] the coolest nerd in the ME universe: a mysterious, strong-willed, and scarred little scientist who delivers dialogue in quick, direct doses".

[8] After hearing of a possible future Mass Effect film, Game Informer's Dan Ryckert looked at the different characters and felt David Hyde Pierce would be their ideal casting choice.

Game Informer's Kimberley Wallace considered him to be one of the best BioWare characters, calling him lovable and citing "his friendly demeanor and tendency to break into song".

[32] Maximum PC called him one of the 25 best sidekicks in gaming, highlighting the moment where he can give Shepard pointers on safe-sex and interspecies romance.

[33] GamesRadar placed him at number 16 in a list of the 50 best game characters of the generation, describing him as "one of the most distinct, personable crew members to ever set foot on the Normandy".

PC Gamer staff member Tom Senior said he loves Mordin "because he shows that you don't need stubble, a gravelly voice and a thousand yard stare to be an anti-hero".