Blue Moon as an Auction
In my overview of Reiner Knizia I made the contention that most of his games are actually auction games, but from the comments on that article I could tell that my point wasn't entirely clear. Fortunately, Blue Moon offers a terrific example of how an otherwise unique-looking game can be based on pure auction mechanics.
Most CCGs are "conflict" games. As it happens, I think that conflict-based games and auction-based games have a lot in common. Thus, it's not too surprising to me that many people look at Blue Moon and see the fighting rather than the bidding. However when you actually dissect the game design elements, I think it becomes a lot more obvious that Blue Moon falls onto the "auction" side of the equation.
To be precise, Blue Moon is a constrained English auction with open turn-based bids, and all payers. In English: the players take turns bidding, back-and-forth, and there are very specific rules for how their bids work. No matter who wins, each player has to discard then entire bid. Many of the bidding restrictions and other rules designed for the Blue Moon auction are somewhat outside of the norm for auction design, but nonetheless most of them can be found in at least a few other auction games.
The constraints of Blue Moon are very tight, and are the core of the gameplay. As in High Society and Beowulf (both Knizia designs), bids are made with discrete cards, and once you've put a card down you can't get it back. Unlike those games, there are even more constraints on your play: you're only allowed to play up to two cards to make your total bid, one general card which must always be played ("character") and one specific card which may be optionally played ("support" or "booster"). Here we can make comparisons to another Knizian auction with tight constraints, Taj Mahal, which likewise only lets you play up to two cards a turn, one "colored", which is required, and one "white", which is optional.
The bidding dynamics of Blue Moon allow for a gradual, but slowly racheting up method of bidding. As in Beowulf and the original For Sale you have two options: to call (bid the same amount) and to raise (bid a higher amount). Most auction games instead require constantly raising bids.
The payment method of Blue Moon, where everyone pays their bids, is slightly unusual, but seen frequently enough that it's got its own name, "the Poker auction". This refers to the fact that players keeping putting bids into a pot, then they all lose what they put in, not that Poker hands are being played. Knizia has used the design in Taj Mahal and (once more) Beowulf, while other notable auctions with very similar payment designs are Condotierre, Havoc: The Hundred Year's War, and the closed bid Fist of Dragonstones.
Finally we come to the truly unique element of the Blue Moon auction system: the turn-based bidding interactions. Effectively, Blue Moon's bidding constantly require geometric increases in bid value, even when you're "calling". This is because you have to constantly replace two of your bidding card types ("charcter" and "booster"), with only the third type ("support") remaining available throughout an entire auction. Thus, bidding exclusively with character cards, if you bid a "2", then a "2", then a "3", you'll have expended a total of 7 resources, rather than the 3 that would have been the case in just about every other auction game.
One other small variation in the Blue Moon auction system is the victory threshold. This is a brinkmanship gameplay element, where the value of victory in an auction doubles when a player has bid sufficient resources. In some ways it offsets the normal Rule of Gambling: that each bid is independent, and that you always have to bid based upon your current chances of victory, not what you've already comitted to the pot.
Overall, Blue Moon has tons that's uncommon or unique in the world of auction design, but when you break it down point-by-point, the ancestry still is fairly obvious. In particular, Blue Moon is similar in many ways to the design of Knizia's later Beowulf, with their shared constrained cards, call-or-raise auctions, and Pokeresque, everyone-pays results. They could easily be the same system, other than Blue Moon's constant, required rebids, and its unique, special-powered cards which draw it closer to the CCG world.
Playing Blue Moon as an Auction
By correctly understanding Blue Moon as an auction, you think about its strategy in some different ways.
I already mentioned the "Rule of Gambling", that you shouldn't stay in an auction if you can't win. There are, however, a number of elements that make this credo more complex in Blue Moon. First, as noted, the stake doubles if a player stays in long enough. Second, you're constantly drawing cards, and thus there's an opportunity to notably better your hand at any time. Third, if you can't do well in the current auction, you might not be able to do well in the next auction either (unless you're more powerful in the opposite "currency"--earth or fire--from what's being used at the current time).
Generally, you shouldn't stay in an auction if you can't win it, and this is especially true if you think you might have a better chance at winning the next auction, either through flipping the element or through discarding and drawing. This should stay foremost in your thoughts in Blue Moon, much as it would in any other auction game.
A second auction-related element that you need to think about in Blue Moon is whether you play low or play high. There are a few purposes to playing low in Blue Moon: to try and get a dragon for a lower expenditure of cards; to cycle low cards out of your hand; to bluff that you have a stronger hand than you actually do; and to build up enough cards to double the stakes. However, playing low also has its disadvantages: you may be giving your opponent a chance to cycle low cards too, which might be particularly useful to him if he just expended high cards in a victorious duel.
A third auction-related element in Blue Moon is the question of whether to call or raise. Much of this goes to the same points as the low-or-high question, but there are also times when it's particularly foolish to call, such as when an opponent is retrieving a character card that he could instantly replay. On the other hand, the higher your "jump bid", the more likely that a savvy opponent will simple bow out, under the theory that you just wasted a lot more money than he did--as if you massively overbid for a check in For Sale.
Playing Blue Moon as an auction game requires a few strategies that might not be immediately obvious, as raised by these various points. You may want to drop out of an auction even if you might be able to win, if you think your opponent bid a lot more than he needed to. You might want to bluff, and imply you have more power than you think you do (though because many players play this as a play-cards-till-I-can't exercise, the usefulness of this could be limited). And, you'll need to seriously think about dilemmas such as bidding-high-or-low or calling-or-raising, as a financial decision, not just a knee-jerk reaction based on what cards you have in your hand.
Blue Moon as Resource Management
At its core mechanical level, I'm pretty confident that Blue Moon is an auction game. However there's another way to look at it: as resource management. Instead of looking at the 6 auction cards that a player has in his hand at any one time, instead consider that each player starts off with identical resources: 30 potential cards. Thus, the ultimate goal is to manage your cost-benefit ratio better than your opponent. If you can gain more dragons than he does by expending the same amount of cards, then you win.
With this in mind, it's worthwhile to consider the composition of the first two Blue Moon decks:
The balance of currency cards (meaning the characters, support, and boosters) between the two decks, really lays out its basis as a resource-management game. The differentiation in currency values is a bit more surprising, but the Hoax deck more than makes up for this with retrievable cards and a few other surprises.
In understanding Blue Moon as a resouce-management game, you can address its strategy from a few different angles, not immediately obvious when thinking about auctions. Namely: are your actions forcing your opponent to spend more resources than you, and if so is that worth losing a dragon (perhaps temporarily)?
Blue Moon as a Card Game
Blue Moon has gotten most of its buzz as a customizable card game. I've saved the discussion of that part of its anatomy last, not because it's not notable, but rather because it's not necessarily the most notable element of the game.
Collectible Card Games of course first appeared with the release of Magic: The Gathering in 1993. There were built on the old trading card model, where cards had different rarities, and you bought a random assortment of cards, then starting building playable decks from those random assortments.
After the initial release of CCGs, two similar card-game types appeared. First were the card-games-that-played-like-CCGs, which were games with special-power heavy cards which were sold as singular entities rather than collectible games. These are mostly American beer & pretzels style games, like Den of Thieves or Portable Adventures, but also have appeared in Euro-designs, such as Jambo.
Slightly more notable is the sub-genre called "customizable card games", which tend also to be games sold in singular, non-collectible units, but which have multiple units that you can combine to form unique, customizable decks. Reiner Knizia has done two of these, Scarab Lords (2002), with sequel Minotaur Lords (2004), and Blue Moon (2004).
Much of the CCG aspect of Blue Moon is pretty standard. You can combine cards in a somewhat arbitrary manner to create a deck that you think will be better than your opponents'. You try and set up good combinations of powers when you do so. However what's really notable about the design of Blue Moon as a CCG is that Reiner Knizia correctly recognizes deck building as a metagame.
Traditional CCGs have used the Magic: The Gathering model, which absolutely balances all cards within the game, so that a player has no better or worse reason to include any card in his deck, other than how it might interact with his deck as a whole. This is typically done through resource costs. In Magic: The Gathering all cards have a casting cost; as cards grow more powerful this cost increases in absolute value, and also might increase in playing difficulty, by requiring multiples of a specific color of mana or multiple specific types of mana. Chaosium's former CCG, Mythos, also used a resource balance. Each card had a sanity value, that tended to run from -3 to +1. Cards with more sanity cost tended to more valuable, and those with sanity gains tended to be fairly weak.
Instead Blue Moon labels cards with a value, from 0 to 4 moons, which is not an in-game resource cost. These moons are used when deck constructing. There are limits on including higher value cards. Thus, there's no longer a need to balance every single card in-game, and deck construction elements are correctly moved from game to metagame, smoothing out the gameplay.
As an aside, Knizia further considered deck building as metagame in his previous CCG release, Scarab Lords. There deck reconstructions happened in between rounds of play from a set deck. It ultimately failed, however, due to a lesser variety in the deck, and the fact that the deck construction was entirely absent if you choose to play only one round of the game.
Concerns & Qualms
Overall, Blue Moon is an elegant, interesting game that combines elements of auction, conflict, resource-management, and (if you want) deck construction. I do ultimately have a few (minor) concerns with it, however.
First and foremost, the endgame is messy. Being forced out of a conflict due to running out of character cards, and then having to discard to end the game is very inelegant, and confusing for first-time players. I'm not sure why the game doesn't end when one player has drawn his deck and is out of character cards, which would be the same thing 90% of the time, and a more elegant, Knizian solution.
Beyond that, I ultimately have some concerns about how the deck construction for Blue Moon works, because I haven't actually done it yet. When the game was originally conceived, it was the decks of cards that were balanced, not the cards themselves. Thus when you move onto deck construction you're left wondering, "Why would I ever include Vetraskedas the Skeptic (Hoax/3/1/no powers) rather than Ledinemras the Monk (Hoax/4/1/no powers)." Clearly, you wouldn't.
My general assumption is that the power level of a Blue Moon deck will increase when you deck construct, but perhaps that's as it should be, because you want to reward good metagaming in a deck-construction environment. I'm planning to try it out later this year, and when I'm done I plan to return here with a few decks that you can use to try and crush your friends.
Until then, watch out for the Buka.