Asymmetry in Plants vs. Zombies Heroes

I've been playing a lot of Plants vs. Zombies Heroes lately and have really come to appreciate the asymmetry Electronic Arts designed into their free-to-play CCG -- elements that could certainly be borrowed for physical game design.

In case you've never played... PvZ Heroes has some pretty standard CCG elements to it: 40 card decks, cards arranged into classes, power for playing cards increases by 1 every turn, 20 life, race to kill your opponent.

While deck construction provides all CCGs with some built in asymmetry, PvZ Heroes adds layers to that by making your opponent play with completely different cards in a completely different way.

Turn Structure
True to the game's name each match pits a zombie deck against a plant deck.  This means that your opponent's deck has zero chance of sharing a card with yours.  But the 4 phases of a turn really extend the asymmetry:

1. Zombie Plays -- but only creatures not tricks (think spells)
2. Plant Plays -- anything the want
3. Zombie Plays -- but only tricks not creatures
4. Fight -- each lane does the usual damage exchange

So the zombie player has to commit their troops first -- generally a disadvantage.  Also, they are limited to only creatures in this first phase, no tricks.  So they have to think through their card interactions.  They can't play a trick and then a creature.  They have to remember to save some brains (zombie power) for the tricks phase if they think they need it.

Plants get to play any of their cards in any order during their phase.  They get to see and react to where the zombie forces are.  But they have to wary of that zombie trick phase.  How many brains has the zombie saved for their tricks phase.  Does that telegraph a play or did they just run out of stuff to do.

Card Differences

This asymmetric turn structure is reinforced by the kinds of cards each faction has.  Zombie creatures tend not to affect other creatures or the opponent when they are first played.  Most zombie cards that affect other creatures or players are tricks.

When a zombie player puts a creature on the board, they often have to sweat out the plant phase before they can buff it.  That buff they hoped to play in the tricks phase may not have a target by then.  Or the plant they were hoping to remove from play in the tricks phase may get buffed out of range of the zombie removal.

On the other hand, if a zombie player is out of brains the plant player can play a creature they can't buff until next turn.  Knowing that the zombie player has few options in the first phase for creature removal.

On the other hand, when a zombie player has brains left for tricks, nothing done in the plants phase is safe.  While the zombie player knows that they will have the last chance to change the board state before combat every turn.

Gravestone and Trick Zombies

Of course, there are exceptions and the exceptions can be very interesting.  There are Zombie tricks that summon creatures (but not a lot).  And then there are gravestone Zombies.  

The Hail-a-Copter trick can summon a particularly large zombie (admittedly the trick is expensive to play).  By being able to play it in the tricks phase, the zombie player may be able to be more tactical about its placement knowing the plant player can not respond until next turn.

A gravestone zombie is hidden in a "gravestone" when it is played.  The plant player does not know what it is and can only affect it with a small number of cards.  Also, the amount of brains spent on that creature is hidden.  So the plant player is left guessing as to what the zombie player did.

When the tricks phase starts, all gravestones are revealed in order (left to right).  A good number of gravestone zombies have affects that trigger when they are revealed.

For me, these exceptions play into the whole structure of the game.  These cards interact with the asymmetry in different ways than a traditional CCG.

First Player Advantage

Another thing I like about PvZ's asymmetric turns is the unique way its deals with the first player advantage.  Magic was forced to tack on rules to try to deal with first player advantage.  Hearthstone built in the coin idea but both are simply add-ons.

I don't even think about first player advantage in PvZ Heroes.  Zombies always go first.  But in the context of the turn structure, I'm not sure how much that matters.

Final Thoughts

This is a level of asymmetry that you usually see in a complex dungeon crawl or hidden movement game.  Among CCGs, this reminds me more of NetRunner than anything else.  I can't help but wonder how creative asymmetry can be used in board game design.  It feels like an area of fruitful exploration.

While not intended as a review, I will close by saying that I do recommend Plants vs. Zombies Heroes.  In addition to my thoughts on the core game design, it works well and does not fall into the pay-to-win trap that hurts many free-to-play games.  I have not spent any money yet and am still enjoying the game.