An amazing game! Great for a beer&pretzels one-shot, but even better for a 20-odd session campaign, which is what it's designed for and where all the best bits get to shine.
PCs start as lowly disposable members of an amoral, corrupt, and penny-pinching military, which has been sent out to wage war for the sake of the Terrans back home. Touchstones are Colonial Marines from Aliens, and Starship Troopers. It can also do 40k space marines but probably only for a one-shot (unless you hack it a bit) because the military structure behind the PCs is so dfferent to 40k.
The combat is simple but clever. Roll under a stat for a success, but you also want to roll higher than your enemy. Intitiative is successes first, highest to lowest, then failures. Going before someone else (e.g. the enemy) allows you to do extra things in relation to them.
The juice in this game though comes from the orders each rank has. As PCs gain new ranks they get new orders they have to follow, and these frequently conflict with the orders of other ranks, and create savoury situations to play out. It's also worth noting that the highest rank can't be atained without you at least once gaining rank by taking a rank from a superior officer who accidently or "accidently" dies on the battlefield. As rank increases the focus on combat decreases, and the players gain the authority to pick their own targets and define their own missions.
Throughout play aspects of PCs are revealed/created, but the final aspect of each PC is already pre-ordained: "Hatred for home". (Home is Terra where the medically-immortal people who sent you out to fight, live). So the ultimate finish to the game would be a PC who has reached the highest rank and now commands the world-dominating firepower of the entire 16th brigade, has orders from Terra to ensure that the brigade never returns home, but also passionaly hates Terra....delicious!
All this good stuff (ranks and orders) isn't likely to come into play as much in a one-shot though, so be aware of that.
Name-dropping: John Harper is a huge fan of this game, and it's the game that inspired Vincent Baker to start writing Apocalypse World.
For context on my tastes and preferences: in recent years I've played and enjoyed a whole bunch of PbtA and FitD (among other things).
[5 of 5 Stars!]