There's fighting then?
MG:U is more of an action adventure game but there's plenty of combat and the designers have decided that a gameplay feature should be the Nondead's indestructibility. You can kill 'em but they don't stay down forever. You can clear out a room but you won't know if the Nondead have resurrected themselves if you come back to it 10 minutes later.

Hmm. What of the puzzles then?
The puzzles follow a more logical pattern than most third-person adventure games. There's none of this 'pull 20 switches in the right order to open a door' stuff; the puzzles are all closely tied in with real-life puzzles and there's an emphasis on action puzzles.

It's beginning to sound spooky.
It's called Martian Gothic because the designers wanted to get away from the normal SF flavour of space adventures, hence the supernatural horror that drives the game's storyline.

Which is linear?
Mostly. Having to switch between your three players makes the game slightly less linear and the designers (Creative Reality Software) have tried to give the player as many options and avenues to progress through as possible. But yes, the story does need to be pushed in a certain direction.

Anything else?
The game save system isn't typical. The game saves (of which there are about 30 for the full 40-60 hours it'll take you to play through) are treated as an aspect of resource management. You have to access PCs on the Martian base (called Vita, by the way) in order to make your game saves.

Sounds intriguing. Res Evil in space!
As Alien vs Predator proved, space can be a very scary place. Now, would you mind not standing so close to me please?