When BioWare was creating the Mass Effect universe, the studio's concept artists came up with a great variety of alien species concepts, many of which never made it into the game and ended up left on the cutting room floor. Although Mass Effect 4 appears to be returning to the Milky Way and fan-favorite original trilogy characters like Liara, there is a reason the new game could also re-introduce many of the aliens cut over the development of all four Mass Effect game so far.
At the start of Mass Effect 4's trailer is a shot of both the Milky Way and the Andromeda galaxy, a shot which BioWare's project director Michael Gamble described as "intentional." This likely means that Andromeda and the Milky Way will become connected in the next game, and with only one cluster of Andromeda explored so far, many of these cut alien concepts could return as new species from Andromeda in the next game to breathe life into BioWare's sci-fi series.
The Cut Andromeda Aliens
There were around ten new alien concepts created for Mass Effect: Andromeda that were eventually cut for time. In the end there was only one companion from a species that wasn't introduced in the original trilogy, Jaal the Angara. While some other aliens were hinted at, like the Jardaan, only the Angara and the Kett actually made an appearance as new organic races.
A piece of concept art shows one of these cut alien races riding on a beast that resembles a giant stag beetle. Based on the design of the humanoid alien, it's possible that they eventually evolved into the Angara seen in-game. With less humanoid races like the Elcor already present in Mass Effect, however, it could be interesting to introduce giant sapient aliens based on the humanoid's mount into the mix.
The Hue-Mon
When it comes to less humanoid aliens, Mass Effect fans need look no further than Mass Effect 1's horrifying cut concept, the Hue-Mon. While the Mass Effect universe is full of humanoid aliens, this concept asked what it would be like for a species that didn't fit in, and was trying to ingratiate itself to the species of the Citadel Council by copying their appearance.
The result isn't pretty, and the description of the concept with its shifting mass of teeth and eyes lying behind its eerie mask might not have fit into the Mass Effect universe. The games have not been without their horror elements, however, and it might be nice to see a species which is utterly terrifying at first despite having a heart of gold. Either way, it's hard to believe that part of this concept eventually evolved into the mask-wearing Quarians.
The Prothean Predecessors
The planned design of the Protheans changed significantly over the course of the trilogy. At first, the idea for the Protheans was taken from an old Star Trek: The Next Generation episode titled "The Chase." This episode saw the crew of the Enterprise discover an ancient race that spread its DNA across the galaxy, and was used to explain why so many species in Star Trek look so similar to humans.
In Mass Effect 1 players can see statues on Ilos that are implied to represent the Protheans. By Mass Effect 3, the design of the species was changed to be more insectoid. What has never really been satisfyingly explained, however, is why so many of Mass Effect's species look so similar, particularly the humans, Asari, and Quarians. This original concept was retconned into one of the species that was wiped out by the Reapers in a pre-Prothean cycle. This species was named the Inusannon, and if Mass Effect's storytellers returned to the alien's TNG roots, it could be interesting to see how such similar life was seeded throughout the Milky Way.
The Alternate Turians
The final design for the Turians is one of the most unique in Mass Effect, landing somewhere between an eagle and a bipedal snapping turtle. There were a great variety of Turian designs originally thrown out there by Mass Effect's concept artists, which can be found in The Art of the Mass Effect Trilogy book.
Many of these designs share very little in common - presumably the idea for the Turians as a military species based roughly on Ancient Rome came about before their physical designs. If any of these concept alien species was given its own unique culture, however, they could completely stand out in a new Mass Effect game.
These concepts range from goofy to downright terrifying, and any one of them could have been the alien race that humanity first encountered in the First Contact War. With Andromeda opening up the opportunity to expand the number of aliens in the Mass Effect universe, hopefully some designs inspired by these weird and wonderful aliens can make a comeback.
The Centaur Shadow Broker
The Shadow Broker was finally unveiled in Mass Effect 2's Lair of the Shadow Broker DLC, before being killed and replaced by Liara T'Soni. He turned out to be a Yahg, a member of a violent pre-spaceflight race that was speculated to be the number one candidate for the galaxy's apex predator once the Reapers had wiped out the FTL-travelling species.
An earlier concept for the Shadow Broker renders him as a huge, centaur-like creature. The Krogan may already be the Milky Way's resident tough guys, but Mass Effect 4 shouldn't miss the opportunity to create aliens with biology that diverges far more from Mass Effect's bipedal humanoid norm.
It remains to be seen whether BioWare will take the opportunity to introduce new aliens in the next game, but if it doesn't the series could risk feeling stagnant over ten years after its debut. While these concepts themselves don't necessarily have to return, it would be great to see the studio get back to the drawing board and make its extraterrestrials feel truly alien again.
Mass Effect 4 is in development.