BioWare has shown off a selection of new concept images from Mass Effect 4, including the homeworlds of two new alien species.

While the races themselves were not shown, BioWare said that much could be inferred from the look of their home planets.

One is a lush, idyllic world where technology and nature appear to be in harmony.

The other new world is something of the opposite. It looks like something the borg would make - dark, angular, hostile.

Other environments suggested the scale of the landscapes on offer compared to your mako land vehicle, including what looked like a barren asteroid and a world of odd rock formations and bubbling pools.

One of the most leading images shown was that of a familiar-looking space station. What may be our first look at the new, rebuilt Citadel features the same faux-sky design, now with what looks like a whole forest in space.

BioWare concluded with a look at a new map interface for players when exploring worlds - something that the developer says it wants to let you do for hours on end - and a look at how navigation through space might appear.

While perhaps not as revealing as expected (due to the current focus on the impending Dragon Age: Inquisition launch instead), BioWare also stated that the game would feature the story of a new main character on their journey to becoming a hero - not someone like Shepard who became one from the moment the original Mass Effect trilogy began.

"With Shepard, you arrived on the scene as a hero, and you were called forward from there," creative director Mac Walters added in a new BioWare blog post. "For the next Mass Effect, however, we've been looking at more of a hero's journey: how you become a legend and what it takes to get there."

A post also details some of the new team members working on the game, including lead writer Chris Schlerf - formerly lead writer of Halo 4.

The existence of two new alien races in the game fits with early details of the project that were posted online back in 2013 after a select group of fans were invited for an early sneak-peek at the game. For more, here's everything else we know about Mass Effect 4 so far.