One of the things that irks people about card-driven wargames is the fact that someone who has learned the deck - who knows what events are in there and what events aren't - has an advantage over someone who hasn't. If I place a bunch of troops or influence or whatever in Spain, but there's a card in the deck (maybe even in my opponent's hand!) that wipes out all the troops, influence, or whatever that are in Spain, it's maybe not such a great idea to pile my pieces into the Iberian peninsula, but I have no way of knowing that. Obviously that's not a mistake I'll make the second time around, but it can be a frustrating experience, and not necessarily the good sort of frustrating.
For some gamers and designers, spending a few games learning what's in the deck is the price of admission, as ordinary as reading the rulebook. It might even be considered a feature and not a bug; one designer I talked to at CSW Expo last year said something along the lines of he looks forward to the thrill of discovery, of walking into traps and lucking into opportunities. And then, once he's on the other side of it, once he's teased out all its secrets, he can play the game at a much higher level, with a sense of mastery.
That's not really my bag, but neither am I too deeply upset myself about being blindsided by this event or that one when playing a CDG. And don't get me wrong; I'm all about games where you have to spend a few sessions - maybe even a lot of sessions - learning how to play the game well. But that's not the same thing as spending a few sessions memorizing the contents and interactions of a hundred plus-cards. It's the difference between learning a skill and learning a list of facts, and actually one of my biggest problems with certain kinds of eurogames is that a lot of them seem more like the latter than the former, more about mastering a series of rules, exceptions, and power combinations than something more organic, about amassing knowledge rather than wisdom. But that's neither here nor there.
I don't mind this thing quite as much with a CDG, at least in my role as a player, but I am less comfortable designing a game that works that way, probably because I do tend to make games that are less convoluted. When I designed This Guilty Land, which can be seen as a sort of card-driven game, my approach was to classify the cards into broad types - Public Opinion, Organization, Laws, and Violence - with all cards within a type acting in the same way. A player only needs to know how many of each that each player has in the deck, and that information is provided on the player aid. There are five "Special Event" cards that work more like a traditional Event Card in a CDG, but learning five cards (which might not ever come out in a given game) is much less of a burden than learning a hundred and ten.
Interlude: I remember hearing Cole Wehrle talk about the events in his game John Company, and he said something along the lines of, the problem with events in most event-driven games is that in order to maintain game balance, the events can't be terribly interesting. The vagaries of the shuffle are already inherently destabilizing, and interesting cards will tend to be really overpowered or severely underpowered depending on when and where they come up. (Paraphrasing there, and inelegantly; I don't think anyone but Cole talks like Cole.)
As a result, any given event in most games doesn't have a very significant impact; the cards become interchangeable. This also removes the problem of a knowledge gap, but it does so at the expense of interesting and disruptive play. Granted, I more-or-less made cards within a certain type interchangeable in This Guilty Land: a Public Opinion card is a Public Opinion card is a Public Opinion card. It's not, however, a Law card or an Organization card. Further, while Oppression probably wants to see a fair number of Law cards early and often, they're garbage for Justice until and only if they can flip the house. I felt that those asymmetries, coupled with the lopsided ways that the cards can enter the Event Display, were interesting and destabilizing enough that I didn't need one-off card effects.
If I ever did do a "real", honest-to-gosh, ops-or-event style CDG though, I'd want the events to be interesting, not fungible. Of course that leaves the question of how to square that with not wanting to make players memorize a hundred and ten or even fifty cards. Ah, well, I thought, that's purely a hypothetical. I can't imagine I'd ever do a real honest-to-gosh ops-or-event style CDG anyway.
So earlier this year I started working on my first real honest-to-gosh ops-or-events style CDG. The Toledo War is about the border dispute between the state of Ohio and the territory of Michigan, and is intended to be this year's Hollandays Sale freebie game. Like last year's Absolutely Aces, the idea is for the game to be a tiny deck that can be tossed into the box with someone's qualifying order. Each one of these decks is produced at a loss, hence the tininess to try and stop us from hemorrhaging moolah.
There are fifteen event cards in the game, used to contest control over three spheres of influence. And these events are interesting enough (to me, at least) and disruptive enough that a person who has learned the deck will have some advantage over someone who hasn't. There are card plays and influence placements that are bad ideas until you're sure certain other cards won't be played to disrupt them, and these mistakes can be fatal.
But: it's a ten minute game with fifteen cards. You'll have seen all of them by the end of the second round. You will probably have the interactions memorized by the end of your third or fourth game. In less than an hour, you'll have attained that knowledge-based "mastery" and can concentrate on the "actually playing the game with skill" mastery.
So the game doesn't really solve or address the "problem" of learning the deck, but it does make it a lot more manageable. The cards themselves can even be a little more disruptive because it's such a short game. It doesn't mean I have carte blanche to put whatever screwy thing I want on this card or that one, and indeed I've had to nerf a couple of cards and combinations that were too disruptive and didn't have natural counters. But if someone's whole position unravels half-way through the game because of a bad move that was capitalized on, they're not sitting there for another hour mumbling under their breath about how they didn't know that card was in the deck.