Insurgency is all about tight, online infantry combat with satisfyingly deadly weaponry. It's one of the best online shooters on PC (for realz), and it is currently disgustingly cheap.
The rest of the PCGamesN team clearly haven't played Insurgency, because it isn't on our list of the best first-person shooters on PC.
If you're looking for a tense online shooter, you can't go wrong with Insurgency. The screen clutter of most online shooters is removed here - it asks you to rely on your eyes instead of looking at maps and relying on hit markers.
Your teammates need to be kept in sight, and you'll only know if you killed your target if you see the body drop. It's like a more tactical take on Counter Strike, and it is fantastic.
And when you're sick of being killed in the many competitive online maps, there's also a robust co-op mode to get stuck into. This is without mentioning the many mods via Steam Workshop integration.
Basically: It's great and is well worth the asking price of £10.99, but right now you can get it for less than £2, which is ridiculous value.
Now go buy it, and then come back to comment about how right I am. Cheers.