Drew Karpyshyn, ex-BioWare developer and lead writer of Mass Effect and Mass Effect 2, has revealed in detail how his original idea for the trilogy's ending could have played out.

The potential plot focused on the spread of Dark Energy - a fact alluded to by several characters in Mass Effect 2 but then never mentioned again.

Karpyshyn departed from the Mass Effect team shortly before the conclusion of Mass Effect 2 and was replaced by Mass Effect 3 lead writer Mac Walters.

Despite describing the plot thread as "something that wasn't super fleshed out", Karpyshyn was still able to give gaming radio show VGS a detailed summary of how the storyline might have developed.

Tali's recruitment mission in Mass Effect 2 centred on a star affected by Dark Energy.

"Dark Energy was something that only organics could access because of various techno-science magic reasons we hadn't decided on yet. Maybe using this Dark Energy was having a ripple effect on the space-time continuum.

"Maybe the Reapers kept wiping out organic life because organics keep evolving to the state where they would use biotics and dark energy and that caused an entropic effect that would hasten the end of the universe. Being immortal beings, that's something they wouldn't want to see.

"Then we thought, let's take it to the next level. Maybe the Reapers are looking at a way to stop this. Maybe there's an inevitable descent into the opposite of the Big Bang (the Big Crunch) and the Reapers realise that the only way they can stop it is by using biotics, but since they can't use biotics they have to keep rebuilding society - as they try and find the perfect group to use biotics for this purpose. The asari were close but they weren't quite right, the Protheans were close as well.

"Again it's very vague and not fleshed out, it was something we considered but we ended up going in a different direction."

The plot thread has become popular among hardcore Mass Effect fans as an example of a better solution than the widely-derided original ending, championed by Walters, the series' new lead writer. But Karpyshyn was keen to point out that his idea would likely have displeased some fans too.

"At one point we thought that maybe Shepard could be an alien but didn't know it." Drew Karpyshyn, Mass Effect and Mass Effect 2 lead writer

"I find it funny that fans end up hearing a couple things they like about it and in their minds they add in all the details they specifically want," he explained. "It's like vapourware - vapourware is always perfect, anytime someone talks about the new greatest game. It's perfect until it comes out. I'm a little weary about going into too much detail because, whatever we came up with, it probably wouldn't be what people want it to be."

Other ideas dropped earlier in the series included series hero Shepard turning out to be an alien, Karpyshyn continued.

"Some of the ideas were a little bit wacky and a little bit crazy. At one point we thought that maybe Shepard could be an alien but didn't know it. But we then thought that might be a little too close to [Knights of the Old Republic character] Revan."

Most intriguingly of all, Karpyshyn mentioned a discarded plot idea for the beginning of Mass Effect 2 that sounds similar to what Walters and the Mass Effect 3 team eventually chose for the trilogy's ending (er, spoilers):

"There was some ideas that maybe Shepard gets his essence transferred into some kind of machine, becoming a cyborg and becoming a bridge between synthetics and organics - which is a theme that does play up in the game," Karpyshyn concluded. "At one point we thought, maybe that's how he survives into Mass Effect 2."