I am already all in on Forged in the Dark as a framework for games. Some of my best experiences have been running Blades in the Dark and its younger sibling Scum & Villainy. That said, I already have BitD and S&V. So for a Forged in the Dark system to pull me in it has to do something notably different both in setting and mechanics. For me, Band of Blades absolutely does. It's a dramatically different experience from Bitd and S&V, and I love it. I adore it. I've wanted this game for years, and it somehow provides that experience.
Like Blades in the Dark, the game is less about individual characters than an overarching organization. In Blades in the Dark, thats the crew. Scoundrels may die or leave, but the gang/crew remains. In Band of Blades, there is the Legion, a mercenary band that has failed utterly and is on the retreat against a threat that is trying to destroy humanity. The foundation of the game is straight Forged in the Dark. There are action rolls, stress, resistance rolls and much of what is expected from a Forged in the Dark game. Added to that foundatio, is supernatural corruption and blight from the undead, as well as a (picked seperately for each game) supernatural Chosen of the gods who is both a benefit and burden.
Where the game diverges is in the campaign structure. Like other troup play style games (eg Ars Magica), there is a different mix of characters. Each session is a mission instead of a job, giving religious relics, moral, supplies or other benefits. Instead of downtime, there are back at camp scenes (freeplay), and campaign actions where the command roles (Commander, Marshal, Quatermaster etc) choose the route, direction and overall progress of the Legion in its retreat from the undead Cinder King.
There was concern among a couple of my players that they wouldnt be able to roleplay, or explore the characterization of a few characters but... That's not what happened. They each had favorite Specialists they'd play when they got the chance. The campaign roles were larger than life figures played for dramatic and comic effect. One player repeatedly played a rookie who was promoted through the ranks, only to die dramatically at the end of the campaign. The players (and I) were heavily invested in our favorites. And sometimes... Sometimes one would die. Sometimes they would die off screen. And it sucked. Because Band of Blades is a war story. IMO the best war stories are not about the glory of war or triumph, they are about the cost, and sacrifice, and often the horror. And Band of Blades is absolutely in that vein. This is Glen Cook's The Black Company, Xenophon's March of the 10,000, and the better parts of Battlestar Galactica. This is XCOM on ironman mode and and Bungie's Myth: The Fallen Lords. When we played, we began to care about each squad (Grinning Ravens!), and each Specialist and Rookie who somehow made it. We wanted to see them all survive and make it to (temporary) safety at Skydagger Keep. But not all of the characters did.
Band of Blades is very, very good.
It's Dark Military Fantasy. If that is a genre you appreciate, love, or are interested in, its worth checking out.