Aside from the central concept, the Flock's strongest feature is its level design. The maps are sprawling, complex things that blend square-ish open spaces with mazelike corridors, and smartly use verticality to create plenty of ambush opportunities. These aren't just for the Flock either; the Carrier can hide behind tight corners to catch unwary opponents in his luminescent beam, briefly turning the aggressor before scuttling away once more.
To make things a touch more complicated, Flock players also possess an interesting ability whereby they can create inanimate clones of themselves, and then teleport between their current position and that of the clone. The idea is to let you set up traps and distractions, aided by the Flock-like statues which conveniently litter the levels. In practice, though, it's easier to find high-ground and jump on the Carrier when it isn't looking.
This leads us to the Flock's biggest flaw. It either cannot or does not elaborate on its core concept in any meaningful way. With three maps and just a single game mode, you can experience everything the Flock has to offer within an hour. Aside from jumping and leaping, the Flock only posses two abilities, the aforementioned cloning skill, and the ability to "Call" to other Flock members, revealing their location. Given that you don't really interact with other Flock players, this is about as useful as speed-dial on a toaster. In addition, the Carrier is supposedly able to focus or widen its light-beam using the mouse buttons, but throughout my experience I couldn't tell whether this was working or not.
More problematic is the lack of variety or progression within the game itself. You become the Carrier, fend off the flock for a while, maybe complete one of the meaningless "objectives", until eventually you're killed and become part of the Flock again. There's an interesting gimmick wherein the entire player base only has a certain number of lives, after which the game will be removed from sale and move into a new "finale" phase. Sadly, there's so little to the Flock, and the player base is currently so small, that it's unlikely the counter will ever reach zero. Developers VogelSap claimed they wanted to tell a story about extinction, but aside from that ominous counter, there's no back-story to the game, no hints at the world's history within its cleverly designed levels.
On top of this are several serious design problems. The character models for the Flock players are ridiculous; skeletal humanoid creatures with jaw-less skulls for heads and bendy-straws for necks. The controls are languid and unresponsive, giving the sensation of pushing your mouse through treacle. Collision detection between the Flock and the Carrier is slippery at best. There have been times when I was certain I'd killed the Carrier only to be burned to a cinder by his light, and other times when I'd sworn I'd caught a Flock player in my light before suddenly respawning as one of them.
Combine all this with some pretty amateurish mistakes, including error messages and command lines appearing on-screen while the game is playing, some very obvious visual glitches, greasy animations and blocky world geometry, and you end up with what feels like a prototype that the developers have slapped a price-tag on and sent out into the Steam charts to die. There may yet be a tale of extinction that emerges from the Flock, but it's unlikely to be the one the developers intended.