Don't go to Mars! That's the message of roughly 100% of all science fiction where people go to Mars. Don't go! Just don't. It's bad there. Scary things happen and there are monsters or aliens and everyone dies horribly.
As you can guess from its title, Moons of Madness fits right in with everything else that's ever happened on Mars, presenting a Red Planet where things are scary and bad. In the first-person horror game you're an engineer stationed on a Mars colony, first experiencing bad dreams and then undertaking lots of Mars chores as you try to keep the base up and running. After some solar panels become unaligned and the greenhouse becomes mysteriously flooded, things quickly go from bad to Mars-bad.
I'm only about two hours into Moons of Madness, but I was perfectly happy with the Mars chores part of it. I'd be content to just drive around in a Mars buggy and gather fuel cells and realign solar panels before heading back to the colony to read my space emails—even without the payoff of glistening horrors eventually leaping out of air vents at me. Moons of Madness looks great, and the first-person stuff is all handled very well, from opening airlocks to using tools and especially wirelessly connecting your wrist-mounted PDA to workstations to accomplish various tasks.
And I don't need nightmares and monsters for things to be scary on Mars. I'm excellent at endangering my own life, like the time I took my helmet off in an airlock before making sure there was actually air in the airlock. That spooked me plenty.
The subtlety of briefly glimpsed shadows and malfunctioning equipment is quickly dropped in Moons of Madness, and things abruptly go from "Hm, some strange things may be afoot here on Mars" to "Ah, that's what's causing all the problems: there's monsters and space magic everywhere."
As for the actual horror in Moons of Madness, it's mostly been routine. A few jump scares, gross squishy noises from around corners, a troubling chat with a space botanist who seems thrilled that her greenhouse is filled with black slime and writhing tentacles, and then all hell breaks loose. And that's another thing about Mars: we need to screen the people we send there much better in advance. Add a few questions to the test about how much they love space monsters. If the answer is anything besides "I completely hate space monsters" then they don't get to go.
We recently talked about if we preferred a protagonist who spoke or one who stayed silent, and one of the strikes against a talkative character is they often talk to themselves. There's nothing wrong with talking to yourself—I do it all the time—but there is definitely something wrong with narrating to yourself: a character who needlessly explains things happening as they see them, and also as you see them. Moons of Madness doesn't do that most of the time, but when it does it all gets a bit comical.
Below (and also here on YouTube) is a little clip—spoiler warning for a few things that happen in the first two hours—of my character looking at things happening and explaining them out loud so I know what's happening, even though I know what's happening because I am sharing the eyes and ears of the character they're happening to.
Standard horror tropes and an occasionally too-talkative character aside, I'm still mostly enjoying Moons of Madness. I'm not familiar with Funcom's The Secret World and it's Lovecraftian horrors, which Moons is tied into, but that hasn't hindered me so far. There are monsters, and I'd rather not be killed by them. That's all I need to know, besides don't go to Mars. But I knew that already.