Why We Have Open Decklists

Posted Aug 14, 2024

Orbs CCG is an open decklist game. That means that the deck contents are viewable by all players in the game.

This feature has a number of benefits. It allows players to strategize against their opponent's deck ahead of time, making the game more strategic. It encourages including one-ofs that you otherwise wouldn't play, because the existence of these cards in your deck might cause your opponent to play around them, or at least consider doing so. It eliminates a class of unfun events, like losing a limited game to a surprise rare or board sweeper you wouldn't have normally played around. It also helps players learn and improve by seeing what other decks are playing, and figuring out new decks they might want to play themselves in future games. Finally, tournaments are often open decklist, so this makes the game more consistent between regular and tournament play.

Sometimes it can be fun to surprise an opponent with a card they didn't expect, however, this is also a downside because it can be unfun to lose to a card you wouldn't reasonably play around. In limited Magic and Hearthstone, you'll occasionally lose to a rare board sweeper that invalidates the plays that came before it. In Orbs CCG, since you can see if your opponent even has one in their deck, you can play around (assuming you're in a position to play around it).

In games with closed decklists, in theory, you might consider playing around any card in the limited format. However, in practice, you often won't bother playing around rares (your opponent is unlikely to have them) or even weaker common cards that aren't used very often. Some of these cards aren't necessarily weak, just specialized, useful in certain situations but not others. In other card games, you often don't bother to play around these cards because the probability that your opponent drafted that particular card, put it in their deck, and has it in their hand, is just too low to make it worthwhile. However, in Orbs CCG, you can include specialized or weaker one-ofs in your deck that you wouldn't normally play, because now your opponent actually knows you have those cards, and will have to consider playing around them. As an example calculation, if you have one of the cards in your deck, you have a 17.5% chance of drawing it in your opening hand, whereas without open decklists, your opponent might mentally consider the chance you even have the card in your deck at perhaps 10% or less, meaning you'd have a 1.75% chance of having it in your opening hand. This is a huge (10x) difference! Knowing that you actually have the card in your deck gives that card more influence than if it's just hypothetically in your deck with low probability. And with the energy mechanic in Orbs CCG, if you draw these specialized cards and don't want to play them, you can just energize them anyway, so it does not take much of a deck-building cost to include some of these in your deck.

Both Magic: the Gathering and Hearthstone have trackers that track how frequently cards are played in decks and how good those cards actually are. This provides a good case study for how average-to-mediocre combat tricks are drafted and played in other CCGs. For example, let's take a look at a card from Magic: the Gathering called Regent's Authority, from their Neon Dynasty set. It is an inexpensive combat trick that pumps up a creature (it does a little bit more but for the purpose of our discussion, just consider it an average combat trick). This card's "average taken at" value is 11.8, meaning it's one of the later cards drafted in a booster pack (taken 11.8 out of 15 or so cards). However, it has a fine winrate and a slightly positive improvement when drawn (IWD) of 1.1pp, meaning it is an OK card if you actually play it. Since it's just an OK card, you will probably have better cards to play instead, which is why it is only included in 11.8% of draft decks according to the stats. This is roughly the same as the "perhaps 10% or less" chance I quoted above. So in Magic: the Gathering, you don't need to draft this card highly, are unlikely to see it even when playing against decks of its color, and therefore are probably not going to bother playing around it. In Orbs CCG, however, you can include cards like that in your deck your opponent will see it in your decklist and sometimes play around it, giving you an advantage just by having it in your deck (and at worst you just energize it).

Mathematically, this is just conditional probability. If you have a card in your deck, and your opponent knows you have it, then they are conditioning on the event that you have the card in your deck. This means that the probability they have the card in their hand is significantly higher than if they didn't know you had the card in your deck. Without an open decklist the formula to consider is P(card in deck & card in hand) = P(card in hand | card in deck) * P(card in deck), but with an open decklist the P(card in deck) = 1, so you are just considering P(card in hand), which can dramatically increase the final result, with important tactical implications. (In fact, the influence of the card can be even greater if you put multiple of the cards in your deck, since that means the card is even more likely to be in one's hand.)

There are some downsides to open decklists too. Some players like surprising their opponents with a weird deck or a secret weapon in their deck. This is a valid concern, however if you really do have a weird deck or secret tech, you still will catch opponents with little to no practical knowledge about how to play against your deck, even if they can see what cards are in it. Without experience playing against that specific card or strategy, they will just have to theorize how to play against your deck, which is not quite as good as having the actual experience.

Overall, open decklists are a feature that can make the game more interesting, strategic, and skill-testing. They make the game better overall. If you're not used to open decklists, give it a try and see how you like it!