One of the grand mysteries of the series has always been the legendary Protheans. The precursors to civilisation, we finally got a glimpse into their society and history in the third Mass Effect game. However, there's still a lot to learn, making some fans hope that Mass Effect 4 will be a prequel, set during the height of Prothean civilisation. Why it'd be great: With a prequel, Mass Effect 4 could help to shed light on some of the series' remaining questions, and give us greater insight into the Protheans themselves. The Mass Effect games have always spent a lot of time dwelling on the history of the galaxy, and a prequel would allow players to explore the past further. Why it won't happen: Mass Effect is all about player choices having a meaningful impact on the future. With a prequel, the outcome is predetermined, which kinda takes the fun out of it. Plus, did anyone actually like the Prothean we met in the third game?