I think that website made a mistake. It doesn't have split screen as far as I'm aware.

Many people thought it would, and some websites listed the game as having split-screen/local co-op ages ago, but the developers of the game never claimed it would have split screen. Only way to do co-op is over the internet with someone else that has the game.

I've been watching someone play through the game on youtube, and will definately be purchasing it when it is released in the UK. The plot twist is actually quite good as there's lots of clues throughout the game.

The characters comment on the fact that the Lutadores seem to be a tribe of dumb thugs brutes that talk in broken English and worship blood sacrifices... and yet they have advanced vehicles and gravity-based weapons. The first boss-fight of the game is an "Unknown Robot" that comes out of hole in the ground and it attacks the Lutadores as well as the players (it seems that's why they are willing to risk giving the Gravlinks to human slaves to do the digging for them). Some of the characters theorise that the Lutadores are aliens, but there's been no spaceships, while your partner suggests that maybe they are some sort of underground civilisation.

A mere hour into the game I had come up with a theory involving time travel. Every sci-fi fan knows there's a connection between gravity and space and time, so I thought the Lutadores might actually be the human race from the future. The "Unknown Robot" came out of some tunnel that had an old sign marked "Gravity Vacuum Chamber" and it made me think that our own scientists did some gravity experiment that ripped a hole in space and time and mixed up two different eras, causing us to end up in a war with our future selves, and this long war would eventually cause us to devolve into barbaric brutes who no longer understand how our own technology works.

However, it became clear that this was probably not the case when going deep underground led into an advanced sci-fi complex that looked like something out of Mass Effect, and that whatever this place it was huge as it had its own train system. This suggested that our world had been built on the ruins of some advanced sci-fi civilisation that existed millions of years ago and then had been mostly wiped out somehow, and maybe the Lutadores were what remained of this ancient civilisation, and living underground for millienia had caused to devolve and become the Morlocks from HG Wells' "The Time Machine".

I guessed the truth about half an hour before the big reveal: the main character's "world" is actually just a country-sized dome on a huge spacecraft, and digging into the ground gets you into the bowels of the ship. There are lots of domes, and the Lutadores are a thuggish civilisation that lives in another dome who have broken out and are invading our dome.

There's a number of clues that the world is not-as-it-seems. You get taken to a desert prison camp one day after the start of the invasion, and the location is "The Wasteland" and one day seems a bit fast for anywhere to become a wasteland. Later in the game there's a cemetary and someone says it must be very old as "people stopped burying the dead centuries ago", despite the fact that the game seems to be set on present-day Earth. Presumably our overlords gave us some sort of cultural dislike of digging up the ground to avoid us discovering machinery beneath the ground, and a belief that everything outside the city is a barren wasteland to discourage us from exploring and learning that we live in a tiny country-sized world.  And actually there's a clue very early in the game: there's a bit where you remember your daughter saying "You promised you were going to take me to the Edge, daddy!" Later in the game a soldier wonders why the Lutadores would take the slaves "to the edge of the world". The "Edge" seems to be a big canyon with more desert beyond it, but I guess it's actually the edge of the world! Presumably beyond it there are holographic walls like the Star Trek holodeck or a high-tech version of Jim Carrey's dome in The Truman Show.

I've only seen two thirds of the game so far so I don't yet know all the mysteries - I think there's an actual reason why the Lutadores have broken out of their dome and invaded ours. The ship's automated defence systems are trying to wipe out both the Lutadores and the main characters as their presence in the ship could "interfere with Inversion", so it seems that something big and nasty is going to happen and the Lutadores are trying to prevent it from happening.