According to a recent interview with CVG, Epic Games had originally been using content from their upcoming construction survival shooter game fortnite in the demos that would be used to showcase various components of the Unreal Engine 4 to attendees of GDC 2013, until a decision was made by VP Mark Rein to hold off so the game could be shown in its own light.

All of the Unreal demos we were going to do here were all going to use Fortnite content. You saw in the tools demos - the rooms, the globes, the animations... that was all created after I said, 'Fortnite is too good to ruin in this demo.' And by ruin I meant showing people a little, tiny bit of it - a little streak of world.

With your first impression of it, you need to understand what it is. So if you don't do that you sort of ruin people's first impression of it. So I said, 'we can't use Fortnite stuff' and they created all of this new content. I'm not talking about the big demo - that was in the works, but they basically started lighting stairways and pieces from that demo instead of all of the Fortnite stuff that they were planning to use for months.

It's because it's so good that we're going to take our time with it, then we're going to have a very slow rollout of it, get a few hundred people to play it and do cool things. It's got such a long lifespan that we just don't want to rush it.

No new clues about the game's features have really surfaced since last July, but it is still being touted as a PC-focused title, and Epic's first in-house release to utilise Unreal Engine 4.