Pool Builders – The Algae of Game Mechanics

Written by Alex Harkey

pbaquariumWe launched a new series over the past year of what we call “Mechanic Archetypes”, an opportunity to examine mechanic-by-mechanic what differentiates successful game designs from the rest when we’re thinking about ones that fall under a label, such as Worker Placement.

Recently we’ve been thinking about “Pool Builders”, a collection of related mechanics like Deck Builders, Dice Builders and Bag Builders that are worth exploring side-by-side as they tend to share quite a few characteristics. In this segment we’re going to step back and examine games that fall into this mechanical category as a group while covering some broad observations as to their strengths and weaknesses. Our goal is that these observations may assist game designers stepping into this growing genre.

Pool Builders – The Algae of Game Mechanics

Since the concept of Pool Builders emerged on the tabletop scene, it has been a popular choice for designers and that popularity doesn’t seem to be slowing down anytime soon. Depending on who you’re willing to debate with, the origin of Pool Builders could go back seemingly as far as you’d like it to, but the approach we’re familiar with today likely began with either Starcraft: The Board Game (2007) or Dominion (2008).

Merely by coincidence did the two games introduce a similar idea of building your personal playing deck during the game and they make for an interesting comparison. Starcraft used deck building to facilitate an interesting combat system by allowing players to build a combat deck that can be improved over the course of the game through buying new technologies and upgrades.

By comparison, Dominion introduced the idea of deck building being the game rather than just a supporting mechanic. Dominion features many of the aspects we’ve come to associate with deck building such as using cards to acquire additional cards and the ability to trash inferior cards that weigh down our deck. Since these two games, popularity of deck builders grew quickly, emerging into related ideas such as dice builders and bag builders. More than eight years later these mechanics continue to bloom.

Data based on items categorized as “Pool Builders” in the BGG database. “Items” includes expansions and promos. A projection for based on current data for 2016 is around 450 items.

On a cellular level, Pool Building embraced something we’ve enjoyed since our very beginning. It’s in our nature to crave those exciting new acquisitions in games; “If I play this card I can but that card AND I’m in great shape to get that one…OH WAIT that sets me up to get that one too.” This cycle is the photosynthesis of pool building games and the satisfaction we get out of it is a better by-product than oxygen. Well…unless you’re holding your breath when planning that next great turn.

In many ways the mechanic has the same built-in motivation of rapid personal improvement we often find in a good RPG; we get better and better as the game goes on, we level up and gain access to new areas or objects, we gain new abilities and replace our old equipment with more valuable items.

Pool builders are games that embody progress; they’re seemingly always more about the journey than the destination. These games are about building the engine and installing it beneath the hood, but a good pool builder often ends before we can ever take it for a test drive or ride off into the sunset.

Anyway, we’re here to talk about the strengths and weaknesses of pool builders, so why don’t we jump right in?

Strengths of Pool Builders

Pool Builders…
  • …elicit a strong sense of player freedom
  • …tend to functionally scale well between player counts


Pool Builders elicit a strong sense of player freedom

playerfreedomOne of the best qualities pool building games can showcase is an experience of seemingly endless opportunity. The wide variety of options and card synergies in Dominion is still impressive and a great deck builder tests the limits of your imagination rather than the strategy you retain in your memory. Ideally the mechanic lays out a blank canvas for every artist sitting at the table.

Let’s look at it another way: if I could wish for one thing in a game, I’d wish for my choices to matter.

Fairly simple request, right? It isn’t too much to ask from a game and I’m probably in good company. What could be better than that?

Now, what if my current choices factor in to my future choices? Way better right? That…that really would have been a way better wish. Now I’m sad that I already used up my wish.

The best characteristic we find in pool builders is that our choices ten rounds in are almost entirely determined by the combination of choices we’ve made up to that point. In a sense, we’re writing our own story like in a choose your own adventure book; our ending is determined by our sequence of choices and every turn of a page.

Pool Builders emphasize the strategy you choose over one that you must choose from.

In pool builders, the things we acquire and the order we acquire things in both matter. That can be quite rare and it is a very impressive trait when we think about how relevant our decisions end up becoming in games.

I’m still thinking about that wish thing; I really should have just wished for more wishes. Rookie mistake.

In pool builders, players determine their own strategy and by the end of the game we’ve not only built our engine, but we’re standing on our own shoulders as the tools we end up using were determined by our past behavior.

Pool builders give us one of the best performance-based measures of player skill: you create the own conditions of your own success or failure. And I really should have just wished for more wishes.

Pool Builders tend to functionally scale well between player counts

ScalabilitySome game mechanics are just more flexible than others. It’s one of the first things you notice when you try to play your favorite Area Control or Negotiation games with two players. They simply become zero-sum games and so much of the fun and flurry of action you saw with four friends on game night disappears and it becomes an underwhelming gaming selection.

Pool builders typically don’t seem to have such limitations, and while there are games that pit players head-to-head and tend to benefit from even player counts (Baseball Highlights 2045) I can’t come up with any games that fails to live up to the player range listed on their box. More often than not, pool builders scale fairly consistently between, let’s say 2-4 or 2-5 players for at least one of three key reasons:

  • Self-contained: Pool Builders tend to be low in direct player interaction. Everyone is improving their own deck, modifying their dice or filling their bag in their own little bubble. You may bump into your neighbor trying to grab the card you want in the central row, but you usually aren’t trying to burn down your neighbor’s house.
  • The mechanic doesn’t implicitly require a minimum player count. Several styles of games become more interesting as you add more players (and thus more parties to interact with). Trading and Negotiation games in addition to Auctions and some Area Control games may include 2 or 3 players as player counts on their box, but really need 4 or 5 to provide the experience the designers intended.
  • The number of players typically doesn’t radically shift the style of play. You probably won’t play Games with a particularly wide range of player counts, say 2-6 players can feel quite different between player counts. Players may change their early priorities or decide to pursue an alternate strategy based on a particular player count.

Whether a game scales well between player counts is usually just a question of “is this game worth playing at this player count?”, for each player count listed on the box. A few reasons a game may not work as well might be that it requires an array of special rules to function for two players, the game loses its “identity” at certain player counts (perhaps by requiring players to play as teams at high player counts) or that additional players add excessive downtime to the game.

Generally, pool building games typically don’t have any of the functional limitations as the mechanic can scale component scarcity or victory objectives easily and effectively between player counts. On the other hand, pool builders often still have issues with Downtime. Games like Orleans have used the low direct player interaction as an opportunity to allocate resources and plan turns simultaneously to reduce downtime but there plenty of deck builders that struggle with downtime, particularly at four players or more.

Neutral Aspects of Pool Builders

Pool Builders…

…have an established formula

Pool Builders have an established formula

To call a creative endeavor like game design “formulaic” rarely has a positive connotation in gaming and can come across as an attack on a game’s originality or a statement that it is predictable in nature. In a broader sense, “formulaic” isn’t always a terrible label and, as we’ll dig into, the description carries with it some positives.


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They tend to follow a blueprint. Dominion certainly inspired a lineage of game designs that followed its mechanical DNA, some of the earliest arguably followed its practices a bit too closely. Ascension had its own deck building descendants that adopted its idea of an ever-changing central row of cards to buy.

The Cerberus Engine is Cryptozoic Entertainment’s blueprint for a line of deck building games across an array of IP licenses, from the DC Comics Deck-Building Game to installments for Cartoon Network and the Lord of the Rings franchise. Legendary is essentially Upper Deck’s equivalent deck building platform for the Marvel Universe and other licenses.

Deck builders can, in some cases, appear quite clique-y in the school of thought that is pool builders; they uniformly apply an accepted core of ideas and many show up looking quite similarly on the table. Deck builders are principally formulaic as a group; a criticism that they can’t escape even as they graduate and become a more mature game mechanic.

From a game design point of view, Dominion spawned a formula that frankly is just difficult to improve upon. How many deck builders were published in the last five years and how many have really moved the mechanic forward? Even a deck builder aficionado could admit that nearly every game that had tried to make one giant leap forward has paired it with a figurative moonwalk backwards in other areas. As innovative as the original deck building concept has been, Donald X. Vaccarino deserves even more credit for honing the formula so well.

They tend to feel mechanically repetitive. Every game has a starting point but pool builders (and deck builders in particular) all seem to have that recurring starting point. Players get their starting tools, they draw, they play, they buy, they discard. Then they do it all over again.

“I’m so glad we’re playing this game, I can hardly wait for my next turn where I’m going to…”

Draw, Play, Buy, Discard. Shuffle, Repeat.

“Hmmm, I wonder what killer strategy Matt is putting together over there, let’s see what he’s doing…”

Draw, Play, Buy, Discard. Shuffle, Repeat.


The first few turns of a pool builder either end up as a learning phase (for new players) or a slow and steady grind (for experienced players). This really isn’t different than many other game mechanics, but it is perhaps more difficult to ignore here as everyone is forced to physically go through the motions of drawing, replacing and shuffling until we reach a point where our strategies diverge.

They tend to play out the same way. If a player wants to play a big money strategy in each of their next ten games of Dominion, not many things will stand in their way. The immense freedom that Dominion can inspire in someone’s first experience is usually all but gone by their tenth game as the heaps of interesting card combinations give way to relatively few competitive combinations. Dominion’s expansions can help the situation, but the problem still exists.

Pool building can feel robotic at times as players silently take turns and follow procedure. If I reflect on the ten most silent games I’ve ever played, at least seven were probably deck builders. They were probably also people I really enjoy gaming with, but everyone succumbed to the cyclical nature of the game. Players start the game with a sparkle in their eye and quickly become deck building zombies until the game is over.

“Alex, you started by saying ‘formulaic’ wasn’t such a bad thing and then you proceeded to rant about deck builders for six paragraphs…”

One reason this criticism exists is that we’re so quick to compare games. It’s the current nature of gaming, we spend time playing a game, then we’re on to the next thing.

The term “formulaic” may not have a positive connotation in gaming, but it does have a lot of value for how we engage with games. Maybe even more in how we value repetition throughout life. Humanity loves cultural repetition so much we created a word for it: Tradition.

Some people can be notoriously difficult about trying new things, so being able to frame new things in the light of past experiences is an incredibly powerful tool as it gives people a sense of familiarity and comfort. That experiential ability to know what I’m stepping into is incredibly valuable in a day and age where thousands of games come out every year and players want to hear about a new game more than they want to try it.

If you’ve played even a few deck builders, you’ve probably got a pretty good idea about what to expect when someone suggests playing one. You may like them, you may not, but you’re probably not in the dark as to what you’re about to experience. The best part about a formula is consistency, and pool builders do that pretty well.

Weaknesses of Pool Builders

Pool Builders…
  • …tend to have a lengthy set-up, a lengthy clean-up or both
  • …can present an inconvenient learning curve


Pool Builders tend to have a lengthy set-up, a lengthy clean-up or both

When we come up with these lists, I tend to run a few of these ideas by others just to see if we missed any great counter-examples that we can highlight. In this case I may have triggered a few people when I mentioned this one. Pool builders take center stage in a breed of games that can be a chore to transition from the box to the table and back.

swimmingpoolmaintenancePool building games are not unlike owning a swimming pool; they both initially sound like great ideas, but over time they can become a headache to have. Owning a pool leads to cleaning and maintenance throughout the year. It’s a hole in the ground you keep working on but never goes anywhere. You end up putting in a lot more time than you anticipated because you want to make sure it it’s ready to use and then you realize you only used it twice last summer.

Similarly, the best part about no longer owning deck builders is that I don’t have to remember how to sort, organize and shuffle the cards. Whoever owns the game can be my local pool specialist and just remind me what I can do to help set-up.

In many ways deck builders are the best cooperative experiences because it takes a table full of people to get some of these games ready just to play, particularly the Legendary deck builders.

Pool Builders can present an inconvenient learning curve

By nature of their components and structure, pool builders aren’t the friendliest encounter for new players.

The Challenge of Self-Assessment: One issue new players can face in pool builders is that it can be a challenge to assess how we’re doing relative to other players. Pool builders naturally reward players who can spot key synergies and build a strong pool of resources around that engine; a skill that comes with experience. Compared to other games (and sports), there usually isn’t a scoreboard to let us know what we’re doing poorly, or a roster to remind us what is currently in our deck or bag of items.

More often than not, we explore strategy games in our first game and get the hang of it sometime in our next few games. It’s a perfectly normal learning curve for plenty of games and if that was it, I wouldn’t be writing about it.

The Challenge of Disseminating Information: Pool builders run into an issue where new players are simultaneously learning the strategy of the game while perpetually having to decipher all the information related to it.

As you might imagine, deck builders can be among the worst offenders, as these games can lose a lot of momentum early on by challenging players with key decisions while they are still understanding their options. Games in which pool building is the game seem to have the most difficulty disseminating information, as new players are pressed to identify iconography or read the text-heavy detailed effects of cards throughout their first game.

Additionally, if the game features constant revelation of new cards (such as Ascension) it can keep experienced players on their toes, but also introduce a lot of new variables when new players are adapting to the basic cards. The whole situation tends to be exacerbated by the expectation for pool builders to showcase variety and offer a range of powerful, interesting or useful items to players every turn while they are still getting their feet wet. You can’t go swimming until you get your feet wet, yet pool builders are frequently pushing new players into the deep end.



Pool building is a fascinating mechanic full of opportunity, particularly given the ideas on display in dice builders and the recent growth of bag builders. Many of these strengths and weaknesses used deck builders as the key example, mainly because they make up the vast majority of pool builders at the moment.

As for more in-depth examples, best practices and the best ideas pool builders have to offer; Matt is going to cover our favorite findings in our third concluding article next time. There are many things we didn’t explore but now we want to hear from you:

What do you find to be the best (or worst) characteristics of Pool Builders?



10 comments on “Pool Builders – The Algae of Game Mechanics

  1. Pingback: The Spoiler-Free Legacy Mailbag (with Hot Takes) – Games Precipice

  2. Joseph E. Pilkus III


    Great series of posts…while flying back from Atlanta last night, I read the last two pieces focused on Pool Builders and found them excellently written with thoughtful analysis across a number of popular games. Even though I generally abhor deck-builders because of the length of time it takes to get things moving, coupled with the overall play time, I appreciated your approach to each of the three (deck, bag, and dice) types.

    I’ve been asked recently to develop a deck-builder for a Canadian designer and one of the things that attracted me to the project was that beyond the initial hand of cards, one’s access to better cards is almost immediate, making play-time a more accessible affair with a game lasting approximately 45 min to an hour.

    Anyway, I just want to thank you again for all of your work in this area and please let me know if you have a Patreon or some other way to assist you in your endeavors.


    1. Alex Harkey

      Glad to hear it, Joe. It sounds like we share some similar preferences as deck-builders have never been a favorite of mine either.

      We did a survey earlier in the year and deck builders (or pool builders) was one of the most requested topics, and what the people want the people shall receive. We dusted off our notes about early deck-builders we’ve played over the years and added all of our recent thoughts. Matt has the third segment on pool builders going up later this week about some of the specific observations and innovations we’ve seen.

      The deck-builder sounds like an great game to develop already. As always, if we can be helpful at some point in the process please let us know. Indeed we have a Patreon located here that helps us to keep writing what we hope the tabletop community finds interesting and helpful.

      If your travels bring you through Atlanta in the near future, I’d love to share a gaming opportunity in-person. Since your recommendation of Raiders of the North Sea back in our Worker Placement series, I finally had a chance to play it and you’re absolutely right – fantastic game.

      1. Joseph E. Pilkus III


        First, it’s great that you’re guided to a greater or lesser extent by your readership. That’s wonderful to hear that you take suggestions from the very folks who consume your material.

        Second, thanks for the information on the Patreon site. For many of us in the industry (even if admittedly not at the center of it), it’s nice to receive some assistance for the time and effort, albeit we know that we do what we do as a labor of love.

        Finally, I’m sorry that I didn’t realize that you were in Atlanta! I’ll definitely let you know should another trip take me to your beautiful city.


  3. Ryan Langewisch

    Great post, I really like the parallel drawn between pool builders and character development in an RPG. I think so many games in recent years have tried to mirror Dominion so closely in their approach to pool building, that it has resulted in kind of a close-minded view of what a pool builder can be. Really anything that lets players customize their array of future options can fit into the category, and I think there are probably many cool and creative ways to explore that concept with mechanics that are nothing like the basic “buy a card” formula in Dominion, and without using cards at all. Sometimes targeting the feelings that a mechanism evokes rather than the mechanism itself can lead to some interesting new ways of looking at a design.

    1. Alex Harkey

      I really like that thought Ryan: “targeting the feelings that a mechanism evokes rather than the mechanism itself”. As you started, the “buy a card” core of Dominion may be an undesirable design assumption and constraint and some ideas I’m inspired by in A Few Acres of Snow may be one such direction; let players compete over acquiring new cards in ways other than buying them outright.

  4. Michael Nanthachack (@LunarKnite)

    Pool builders are definitely one of my favorite mechanisms in a game, so I thoroughly enjoyed reading this. It’s also the one that I wanted to start making games based around it, because while the core mechanical systems are going to be the same and there’s just so many of them, I don’t think it’s interwoven into other systems as much. The few notable mentions would be Starcraft, Trains, Rococo, and Copycat from the top of my head. So I definitely think there’s room for growth by adding parts to the game even if there’s not much you can change to the core concept.

    1. Alex Harkey

      Great recommendations, I definitely find plenty of design inspiration among games that use it as one idea interwoven into several. I think the popularity of the pool building is going to be a huge boost going forward as designers can incorporate it as a contributing mechanic into their games without it being a tremendous innovative hurdle for players to grasp. Of course I’m still fascinated to see what designers do with pure pool building games as well, the opportunity still exists and there will be plenty to learn as the mechanics continue to age.

      I really enjoyed your thoughts here Michael, thank you for commenting.

  5. Concurrent Games

    This is excellent! Thank you for what you guys do, it always catches my interest, no matter what you’re working on. Among the projects I have now, I’m working on a deck builder at the moment and the set-up and clean-up even makes play testing seem like labor for anyone other than me. It isn’t a problem I can conceal, so how do I fix it?

    1. Alex Harkey

      I wonder the same thing, although I’m tempted to think there isn’t any single solution, but rather a handful of ideas that can each reduce the problem some. The short list might be:

    2. a really great insert
    3. minimizing blending/shuffling of deck types (as they must be selected and shuffled pre-game and sorted/organized post game)
    4. developing a way that players can return cards or objects from their pool directly to the correct area of the box.
    5. As for set-up:
      Most players don’t have much they can help with other than say shuffle cards (as I found myself doing with Legendary Deck Builders) or maybe helping to arrange the board as things are being pulled out of the box.

      Pool builders often rely on someone to “run the show” and get the whole ordeal set-up, as often you can’t easily delegate a role like dealing cards to someone or randomize a bunch of tiles. Teaching can’t really overlap with set-up either as you typically need the cards or components to effectively display what they do.

      Another reason players are often sitting idle during set-up is that rather than receiving a bunch of pieces in my color (for which I can spread them around the board on various starting tracks and locations), I start with very little.

      As for clean-up:
      Game play consists of taking a sorted pool of objects and effectively scattering them around the table in peoples personal pools, decks or bags. Clean-up is mostly unscrambling what the players did during the game.

      It would be a natural fix if someone could reverse the situation and develop something like a reverse deck builder; players start with a wide array of things and return them to the supply piles over the course of the game for easier clean-up.

      Really great question and interesting to think about. Thanks for commenting!

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