Inverse Worlds is a good book and worth the money for any fan of Dungeon World. Its player facing content is a major step up from the core classes as the focus on higher fantasy gives the classes moves with more "oomph." It has a great deal of GM facing content to make adjusting to its setting a breeze and helps greatly for those who keeps to DW's model of "No preparation." Perhaps its best decision is removing the cruft DW had by trying to be D&D.
Inverse Worlds is a good book and worth the money for any fan of Dungeon World.
Its player facing content is a major step up from DW's classes as the focus on higher fantasy gives the classes moves with more "oomph." Here are some examples of what some of the new playbooks are like.
The Mechanic is of particular note. Making a class all about being a bloke in a mecha and having it be both fun, balanced, and effective (I was playing one in a one shot, recently) is a nice surprise. It has a lot of versatility in its design, but never becomes overly complicated or too versatile. You can build the type of mecha suit you want, with little fuss, have it be effective, and not be unbalanced. Also, the Megas XLR reference was sweet!
The Captain, for example, is an airship pilot that gets a free airship and means to get it back if its lost (I've seen another review comment on the means negatively, but the point of the abstraction, in my mind, is to avoid the class losing a key resource because you are low on gold: you could, for example, view the abstraction as pulling in favors, some stashed away savings, etc.). Despite what one might think, having an
airship is surprisingly undistributive when you have it and non-crippling when you don't. Outside of its airship, the pilot is great at trading and navigation. In the case of the later, it can make travel safer which is a nice considering how much adventures do that.
The Collector can best be described as a "the bottomless bag." The classes main shtick is that it can pull items out of its bag to help in a situation. Thanks to DW's (Really AW's) system, this is kept in check by a series of well thought out limits that keep the move useful, but not overpowered. I can't help, but feel the Collector is Inverse World's answer to the the thief and, if so, it's a fun and, possibly, innovative take on the idea.
I'm not going to go through every class in the book like this, the above was just to give you an idea for what the playbooks are like. The book also includes The Golem, The Walker, The Latern, The Survivor, and The Sky Dancer. There wasn't a class I disliked in this book. It was a good selection.
The Compendium classes (think Prestige Classes without all the requirements, just do a thematically appropriate thing within the game itself to unlock) are fun, but I would have liked to see more of them. While I get Compendium Classes are tied very tightly to a setting so people tend to want them less, I still think they are a cool concept and really help tie characters to the world.
As a fan of balanced classes, the playbooks are a nice change of pace as some 3rd party playbooks that try their hands at higher fantasy tend to be poorly balanced narrative-ly (In DW, disparity more comes from how classes affect the narrative than their actual numbers since it is a low numbers game). Inverse Worlds successfully avoids this issue of balance.
It has a great deal of GM facing content to make adjusting to its setting a breeze and helps greatly for those who keeps to DW's model of "No preparation."
It has an Instant Island Guide which makes creating a new island for your players fast even during midgame. It has a few premade areas you can implant around your players if need be. These areas even have some custom moves to make them feel distinct. Setting wise, the book does a good job of telling you about the world, not individual places. By keeping to the overall picture, it makes it easier to build the IW setting around my ideas for the game than build my game around the IW setting.
In regards to the setting, it's a fun and cool idea for a setting. If this were a novel, I wouldn't call it original, but, as a TRPG, the setting stays away from a lot of tropes that makes alot of TRPG settings same-y and does a good job of backing up its setting with mechanics (like the playbooks and a slew of near gear). The vehicles rules keep it simple -- which is inline with the system -- and are a fun addition to the DW format.
Rules were given to fit your favorite ideas from the supplement in your normal DW games that might be hard to convert. For example, rules to use the Captain in a setting without airships. It's a very smart addition
and, honestly, a necessity for a book calling itself a supplement.
Perhaps its best decision is removing the cruft DW had by trying to be D&D.
While alignments were just a way to get extra XP, they had some limitations to them thematically and felt restrictive. If I like the XP trigger for lawful, then my character is going to have to be a lawful character. The replacement with Drives -- which focus on smaller aspects of the player's world outlook instead of the all encompassing nature of alignment -- allows players to choose XP triggers they like without having to conform all their behavior to a particular set of beliefs. My Captain can be a roguish and chaotic figure, but has Responsibility and Respect for his crew (a common thing in fiction) so protecting them gives him XP. In DW's alignment system, I'd likely have to be a lawful character to get that XP trigger.
Race to class restrictions are gone. You can now play any race with any class unlike DW system that was emulating old school D&D. In place of racial moves, each class has their own special moves which feel more thematic as a result.
DW made the mistake of trying to be a different game that it was not, IW tries to be its own games.
Like I said before, IW is a good supplement for DW. It capitalizes on DW's strengths and removes some of its weaknesses. Its content is good on its own, but could fit into your regular DW game if you just want to take your favorite things. Visually, it's a bit minimalist, but, for an independent developer, that could be forgiven. If you didn't like DW because it was too simple, too focused on narrative, lacked crunch, or any reason similar to that, you probably won't like IW. If you didn't like DW because its classes were a bit boring and it tried too hard to be D&D, you might like IW.