I really wanted to like Iron Edda: World of Metal and Bone. I read the negative reviews and figured since it was a Powered by the Apocalypse (PbtA) game that I’d be able to home-brew around them. After attempting to run several sessions it became clear that the flaws of this game outweigh the interesting bits.
The biggest issue, is that the setting and premise, of Viking style warriors riding giant bones and fighting Dwarven mechs is not supported by the rules at all. The best PbtA games have their mechanics centered around the premise of the game, but the playbooks and mechanics of Iron Edda are for a semi-historical, low-magic Norse flavored game and not for a game about epic warriors fighting legendary adversaries. The +Giant tag does not provide any mechanical effect by the book. I was treating +giant enemies and PCs like Apocalypse World gangs but then when I re-read the rules trying to figure out how to fix many of the issues I realized that was something I had added on myself and not something that was even hinted at in book, that a +giant creature would do additional damage and take less in return. The playbooks are not well balanced, tending to either be very combat focused or having nothing to do during combat, which quickly became an issue when I ran for my group.
Another big issue is since the game does not use either the standard six fantasy attributes like Dungeon World or the 5 Apocalypse World attributes (Hot, Cool, Hard, Sharp, Weird), it is extremely difficult to pull in moves and tricks, or anything really, from any PtBA game. But the rules themselves are pretty sparse, even for a PbtA game. Lots of moves are copied almost verbatim from Dungeon World and the game-master advice doesn’t add anything new, interesting or especially useful.
Overall, the only interesting thing I saw in Iron Edda was the wound system, but I am not sure if that was original to that game. If you’re really interested in the setting and concept, maybe check out the Fate rules version? I’m not at all familiar with Fate, but that set is at least better reviewed. The end product feels like it could have used an additional round of play-testing and GM advice more tailored to the game. When I got the Fate version for comparison, it was clear that many of the most polished parts of Iron Edda: World of Metal and Bone were taken from those rules. Otherwise, there are plenty of other PbtA games that are much better developed.