It's a great idea, and precisely what I like to see first-person games doing. Sadly, Betrayer isn't as compelling as it might sound. The problem with its method of storytelling is there's no way to combine the clues you find into a deduction. In the end all you're doing is either collecting everything in the area to progress, sucking up these leftover clues like Columbo's vacuum cleaner, or searching for a specific right clue in order to complete a quest. Consequently, you're less of a detective and more of a collector.
Compounding the problem is the fact that the day/night transition means you need to trudge around each area twice before you can move on, and this quickly becomes tiresome, especially since there's often no indication of what you're looking for or where to look. To combat this, Blackpowder introduces a mechanic whereby pressing X lets you 'listen' to the environment, triggering a (fittingly eerie) noise that emanates from the direction of a point of interest. Again, this is another neat little concept, hinting at how to progress without explaining it directly. But forcing the player to carefully search for the destination is no good if the journey in the meantime is no fun.
Betrayer encourages a stealthy approach to combat, and once more it approaches this in an intelligent manner. Enemies have realistic lines of sight, so it's important to keep low and use the undulations of the terrain to obscure your silhouette. Their hearing is pretty sharp too, and it's wise to wait for the intermittent gusts of wind that blow across the environment before moving closer to a target.
But the combat itself is frustratingly flimsy. The weapons have little punch to them, and enemies crumple like a cardboard toilet when killed. Worst of all are the ridiculous sound effects that trigger when an arrow or a bullet hits an armoured enemy. They're reminiscent of a comedy soundboard on a radio show. It's completely out of character with the rest of the game, which is especially odd given Betrayer's otherwise excellent sound design.
This might not be such an issue if combat weren't a regular occurrence. Yet even if you're being sneaky, dispatching one enemy will usually alert others in the area, causing them to run dumbly at you in a straight line. Certain enemies, such as the Flaming Indians (I have no idea if that's the correct term for them, but that's what they are) are a little trickier. But that doesn't change the fact that fighting anything in Betrayer simply doesn't feel good. Since Blackpowder consists largely of ex-Monolith devs, the creator of cracking FPS games like F.E.A.R and No One Lives Forever, this is a surprise, and not a pleasant one.
In the end, Betrayer is a bit of a disappointment. Its bold art-style and its attempts to innovate in every little system are worthy of admiration. But in this instance they aren't sufficiently developed, and cannot conceal the fact that Betrayer falls down on the basics.