One of the highlights, nay, the money shot of the game is the airship system. It's simple, but it's also really fun. Specifically, I'm wondering about the ins and outs and pitfalls of this adapted approach. That said, here are the paradigms I'd like to push:
- Probably the most important assumption: the game has separate minigames for standard action-adventure protagonist activities that are not covered by the vehicle, vehicle combat, and crew system. You know, shit like delving in dungeons, running businesses, fighting monsters, all that. Think Shadowrun or D&D or, heck, Skies of Arcadia. Keep this in mind, because it influences the other assumption.
- The game heavily encourages a 3-7 PC party to pool their resources together for a crew. If people want to have their own individual vehicles then it works Voltron or Power Rangers style where while people can dick around in their Megazord component for any serious combat you need to, well, form Voltron.
- The game should be able to support this system and also have people with real and important superpowers. It's okay if the answer the system gives to 'what happens if a hundred 15th-level wizards spam fireballs from embattlements at the vehicle' is 'the vehicle gets slightly damaged, but it pretty much annihilates them in less than a minute'. It's also okay if it turns that vehicles have an upper ceiling on power and Superman or Szass Tam can contemptuously destroy any number of airships. But the game should be able to model what happens without Rule Zero.
- The individual badassedness of the officers and crewmembers matters a lot. A decent crew with a technologically superior ship should only be able to hold parity at best with a great crew with an inferior ship.
- The game doesn't enforce hard game balance caps for determining who will join your crew and what kind of vehicle you'll have. Oh, sure, there can (and should) be plenty of soft caps like Reputation and Leadership and maintenance costs and simply the kind of people you attract, but if you come across Dread Pirate Roberts with his sexy +14 to Navigation and Gunnery bonus and he agrees to serve on your ship, the game and the DM shouldn't implode in on itself. That said, some sort of CR system which compared the individual D&D-like badassery of PCs to their expected wealth and power and tried to match them with an average-case vehicle and crew would be helpful.
- The game has a logarithmic utility function for additional crewmembers. Since you can't enforce a video game-like hard cap on the number or ratio of gunners or medics in your crew, there needs to be a way I'm thinking of something like an Attention or Morale or Bureaucracy modifier where the competence of all NPC crewmembers drops off if you add too many people.
- The crew roster has a bunch of specialties and positions that need to be filled in such a way that you just can't mix-and-match a generic badass nor can you just load up on 20 Magic Engineers and call it a day. You need shit like a gunner, a cook, a delegate, a medic, soforth. And while in-universe a good helmsman might be more valued than a good marine or a good boatswain's mate, as far as the players are concerned it's like wondering whether the feet slot or neck slot for magical items is more valuable.
- The NPC members of your crew are individually important without hijacking the narrative unless the PCs and GM can think of a good reason for them to do so. Think Fire Emblem or Valkyria Chronicles or Mass Effect.
- With all of the above assumptions, it seems like the narrative limit for crewmembers is 25 NPCs or 6 NPCs per PC, whichever is larger.
- The vehicle regularly undergoes upgrades. This means that the game will have to provide a lot of different methods for doing upgrades, including but not limited to: commissions, off-the-shelf purchases, scavenging from defeated ships, scavenging from wrecked or abandoned ships, research, trading technologies from around the world, so-on.
- Very importantly, the crew that runs the vehicle is only really good for running the vehicle. They do not generically assist in personal melee combat, adventuring, politics, or anything. As is often the case, an analogy with Star Wars might be helpful here: C3P0 is your go-to guy for communication and delegate duties, but no one -- stupid prequel trilogy moments aside -- expects him to participate in even light adventuring.
- Because of the above caveat, there needs to be a way to enforce segregation between the skills needed to pilot the vehicle well and Other Wars of Adventuring. This means that while it's okay for a particular wizard to be a great engineer, wizards in general can't make great shipboard engineers. What's more, specialist skills and abilities of non-adventurers need to be better than adventurer dabblers. It's okay for a champion Waterbender who has never been aboard a ship before who uses her powers properly be a better helmsmen than 95% of the shlubs out of the academy, but this alone shouldn't make her the World's Best Helmsmen. This makes me think that not only should skills advance at a different track from traditional Adventurer powers, but they should also increase faster.