Wednesday, July 27, 2011

REVIEW: CellCraft - Learn Cell Biology without the Textbook

Type: Online Flash game, downloads available for Mac and PC

Price: Free

Target age group: 11-15

Genre: simulation, strategy

What kids are learning: Learning cell biology is not easy, and CellCraft's on-rails mission style really crams in the facts.  While this may be helpful for students currently studying cell biology, unfortunately, more casual players don't get much of a chance to understand all parts equally, nor is there much opportunity for free exploration into the life of a cell.


CellCraft is an ambitious game which strives to create gameplay that will be satisfying to the casual gamer while also providing players with a fairly detailed lesson in the basics of cellular biology. The game is available for free online play through major flash gaming sites newgrounds and kongregate, and also is available for download (also free) from

CellCraft wastes no time tossing players into the realm of the cell and your primary mission throughout the game is simply to survive.  In the first level, shadowy figures introduce players straight off to some of the basic mechanics of the game, like how to make the cell move and gather resources.  Completing the level takes players to a cute cutscene, in which the main plot of the game is introduced.  The remainder of the game is organized around this basic structure: in the "action" portion of the game, the player controls the cell and satisfies various survival criteria.  This is followed by a cutscene ensues which advances the overall game story.  The game has 8 levels total, which range in difficulty from the basic "tutorial" levels to the fairly challenging final stages which involve meeting multiple criteria in order to succeed.


As mentioned above, the gameplay in CellCraft all takes place at the level of an individual cell.  Players must quickly learn how to control their cell, gather resources, generate new organelles, and fend off various environmental threats like cold temperatures or viral infection.  To those who have spent any time playing strategy/simulations (think Civilization or StartCraft) or tower defense games (Plants vs. Zombies, Gemcraft), the mechanics will generally feel familiar.  Overall, CellCraft does a good job of putting these popular game mechanisms in the service of teaching cell biology, however, there are times where the game's ambition tends to outstrip its capabilities.

Resource management
Managing resources is a task required by many of today's most popular games, however, where most pure entertainment games require players to collect resources like money, troops, or raw materials, CellCraft requires players to keep a close eye on levels of glucose, ATP, amino acids, fatty acids, and nucleic acids. The right amounts of each are needed to generate new organelles or to build defensive structures for warding off viral invasions.  But not all of these resources are obtained through the same means.  Glucose is generally obtainable from the environment by moving your cell over various glucose icons scattered across your petri dish, but ATP can only be generated by mitochondria within the cell. Such mechanics make sense both from the perspective of actual cell biology and as an in-game mechanic (you need certain resources to produce others), but I certainly felt that more careful balancing was needed in order for this mechanic to really challenge players in a non-trivial way.

Resource requirements, or "Action Costs," are not very prominently
displayed and may be somewhat mysterious to non-biology majors. 
For all of the in-depth explanations given in the game about how the cell produced various organelles, it was nevertheless hard to get a feel for why producing certain organelles had the costs that it did.  Of course, in a conventional strategy game, the precise resource requirements for building a particular structure might be largely arbitrary.  Yet, players will still inherently understand why building a house-like structure might require some combination of say, gold, lumber, and stone.  I doubt that players will get any sense from CellCraft of why building 5 slicer enzymes might cost ATP, nucleic acids, and amino acids whereas dividing a mitochondrion will cost ATP, nucleic acids, amino acids, fatty acids, and glucose.  Nor is it fully obvious to players on their first run-through of the game which organelles will only consume resources like nucleic acids temporarily, versus those that will consume them permanentl.  The fact that resource requirements for a new cell component is also inconveniently displayed doesn't help--the text and icons are very small, and only revealed when players mouse-over the item they want to build.

The failure to distinguish resources in a meaningful way definitely affected how I played the game.  Rather than look at the requirements and plan in advance, I tended to just click first and ask questions only if the component could not be built.  This strategy did occasionally lead to problems (my cell once died a slow and painful death when I used up both my nucleic and amino acids on mitochondria and did not have enough lysosomes built to recycle them), but in general my ability to succeed in CellCraft without paying hardly any attention to most of my resources just reinforced my suspicion that resource management was employed rather trivially.  Unless I made especially bad choices, I found that if I could manage to maintain a surplus of one resource--glucose--then I generally had a surplus of all resources and could "develop" my little cell with wanton abandon.  Although it is obvious that players are asked to monitor five different resources in order to stay true to the actual functioning of a cell, I had hoped that there would be more strategy and tough decisions involved in deciding how to spend my resources. Perhaps it's a testament to the hardiness of cells that mine could stay alive without much meddling on my part.  Still, the resource management aspect of the game was something of a disappointment as a play mechanic.

Tower Defense
The second core play mechanic in CellCraft is a "tower defense" kind of play style.  That is, waves of invaders (in this game, viruses) will rush your cell, and you must have built a sufficient amount of appropriate defenses to survive the invasion.  A fundamental component of this style of gameplay is a variety of invader types, each of which is more or less susceptible to particular kinds of defenses.  In CellCraft, players are told that Injector viruses are defeated by slicer enzymes, Invader viruses are best combated with lysosomes, and Infestors are blocked by defenses and destroyed by lysosomes.  But as with the resource management element of the game, even though the tower defense style action apes some of the most popular Flash games available today, the mechanic is shallow and doesn't truly lend itself to fun and addictive gameplay over the long haul.

One weakness of the hoards-of-invaders mechanic is that the differentiation of defense types is not as distinct as the information in the tutorials leads players to believe.  For example, even though lysosomes are supposed to be effective for combating Invader viruses, lysosomes alone are not likely to stop these viruses quickly enough to avoid replication in the cell.  In fact, in the tutorial level in which both lysosomes and Invader viruses are introduced, having a 4:1 lysosome to Invader virus ratio still resulted in the virus replicating and me receiving a performance grade of C. This was only marginally better than I did with an equal ratio of slicer enzymes to viruses and no lysosomes. It is clear then that the only way to consistently squelch viral invasions rapidly and effectively is to always have some lysosomes on hand and numerous slicer enzymes, regardless of the type of viral hoard making its assault.  It was ultimately not clear why the tutorials instruct players to try and match appropriate defense structures to the specific kind of viruses attacking, when strategizing in such a directed way inevitably resulted in viruses reproducing inside my cell.

Even when zoomed in, it is surprisingly difficult to
track the action in your cell as a viral invasion unfolds.
A second problem with the tower defense portion of the game is that graphically, action in the cell is hard to follow. Unlike many other tower defense games in which enemies attack along defined paths, often in a single-file line, viruses in CellCraft arrive simultaneously from all sides, meaning that players cannot expect to look for these invading enemies in any one particular place.  And viruses are quite small, both as they approach the cell and as they attack and replicate in the cell.  Sometimes, the only way players can know if they're still trying to finish off a viral invader is by the musical cues, as one or two viruses may easily go visually undetected. The game does have a zoom feature, but I found it to be both buggy* and only an incomplete solution to the problem.  In order to keep your cell moving and gathering resources, you need to be zoomed out to see as much of the map as possible.  But in order to pay any attention to what's happening inside the cell, you need to be zoomed in.  The slider bar on the left side of the screen was both too slow and choppy, and inconvenient to select when you're also trying to click on various parts of the cell to mitigate viral damage or move and gather resources.*

Finally, I found both the pacing of the tutorials and of the virus attacks to be problematic.  Things move too quickly for players to really get a feel either for how their cell works, or to be able to respond intelligently to viral attacks.  Players who follow the onscreen instructions the begin each level and click "continue" immediately upon completing an assigned objective will quickly find themselves helpless and overwhelmed by sudden viral invasions.  Although there is no obligation to click continue right away, it also is not clear why the game did not build-in time for exploration and development of the cell into the levels.  At the very least, a simple warning message telling players that they might want to build up defenses before they click "continue" would be helpful.

Do I really have to recycle all my defenses?  But why?!
The problems with the tutorial structure and level design goes slightly beyond mere pacing problems. Some of the objectives in the tutorials will actually work against players' chances of success in the level. For example, in Level 3, "Insane in the Membrane," one of the first objectives players must complete it to recycle all their slicer enzymes. The rest of the tutorial focuses on expanding the cell membrane and building peroxisomes--when the cell is unexpectedly attacked by viruses, it is entirely defenseless.  In a later level, players are similarly forced by the tutorial to create parts that are not wholly necessary to the cell's immediate survival (like 4 peroxisomes), which means that cell's resources are that much more limited when players suddenly need to create defenses for an impending attack.  Why players are put in these kinds of conundrums is not clear, especially because the fast paced nature of the viral attacks themselves make it incredibly difficult for players to respond to ongoing invasions on-the-fly.

Just as the action is difficult to follow because of the small size of the graphics, is it also difficult to follow because of the speed of the invasions.  Unlike traditional tower defense games, enemies in CellCraft don't give players very much chance to track the action and adapt to weaknesses in their defenses in real-time. Instead, the invasion structure in CellCraft is for viruses to simultaneously swarm your cell, sometimes 30-40 at a time.  All you can really do at this point is furiously build and rebuild slicer enzymes (they rapidly break apart in "battle").  However, slicer enzymes take time to build, and only so many can be built at a time because your nucleic acid reserves are usually small.  So going back to the example of Level 3, players who easily complete the tutorial objectives and blithely click through the lesson quickly find themselves with mere seconds to build slicer enzymes to defend their cell.  This is in essence and impossible task.  And while the lesson is fairly forgiving and most players will not die in this level, it nevertheless gives players an unpleasant taste of the frustrating inadequacy of the game's controls and mechanics for the kind of fast-paced action presented in subsequent invasions. Not to mention that the amount of attention players must give to constantly rebuilding slicer enzymes essentially dominates any kind of strategy players might develop for dealing with invasions.  I found it to be pretty much impossible to focus on anything else that was happening in the cell, or to notice how well the cell's other defenses (lysosomes, defensin) are doing at managing the invasion.

I'm moving to the head of the class!
It might have been help if players had been given some ability to speed up and slow down time once an invasion had commenced.  While this may obviously decrease the challenge factor, it is a common device used in tower defense games that gives players some chance at setting up adequate defenses against waves of unexpected invaders, and also allows players to can hurry through levels that are relatively easy.  Similarly, feedback after a wave of viruses is defeated could have been more instructive.  Players receive grades based on their performance, but the grades don't help you assess what went wrong and why.  Sure, you know you were overwhelmed by viruses--knowing the number that kicked your cell's butt doesn't help.  But why were you overwhelmed?  Were your using the wrong kind of defenses, did your defenses run out without you realizing?  Even including such simple information as the number of particular cell defenses built and destroyed would give players a better sense of where their defense strategy may or may not have gone awry.

Educational Content

Where CellCraft excels is in the depth of the scientific material presented throughout the game.  It did not take me long to realize that I have much to learn when it comes to cell biology.  My memories of high school biology are quite fuzzy these days, and the little than I do recall can hardly be considered useful: ATP is really important and it's embarrassingly fun trying to say "endoplasmic reticulum" aloud 5 times fast.  Right.  It's safe to say that more of what I know today about cell biology comes from the Jonathan Coulton song "That Spells DNA" than from what I can recall from AP biology.  It was therefore with high hopes that I began playing CellCraft.

CellCraft fortunately does not leave one wanting when it comes to information about the components and functions of cells.  In fact, the learning curve with respect to the cell biology is actually surprisingly steep. In the very first lesson alone, you are introduced to centrosomes, cytoskeletons, cytoplasm, pseudopods, ATP (adenosine triphosphate), glucose, and mitochondria.   After a short cutscene, the barrage begins again and organelles like the nucleus, ribosomes,  amino acids, nucleic acids, slicer enzymes, viruses, membrane health, are introduced.  This material, I can imagine, would have been superb in reviewing a lesson in cell biology before an exam.  That is to say, the game functions as a great companion piece to reinforce information about cell biology, but I would not consider it a great introduction if this material is all new to you.  As an introduction for the uninitiated, the amount of information presented is definitely too much, too quickly.

The detailed information far exceeds what players
need to know to effectively play the game.
The detail which the game goes into regarding the function of the various organelles seemed like it might be somewhat off-putting for players who aren't concurrently enrolled in a biology course.  I definitely found myself overwhelmed by information pretty quickly, and I eventually gave up watching the slideshows and animations that showed me how certain new parts were produced by the cell.  It was enough to try and keep track of what I needed to click on and when to stave off an unexpected virus invasion.  I imagine that players get the most out of this game only when they're actually studying cell biology in school.  But even then, students might find themselves more familiar with more specialized parts than with basic parts.  This is because gameplay in CellCraft tends to reinforce the material presented in very uneven ways. Things like slicer enzymes will become well-known to the player based on their incredible importance to the game.  However, even though ribosomes are introduced in some detail, players will generally never have to make them beyond the very first tutorial level of the game.

Another minor limitation posed by the game's attention to detailed biology is the way it affects the queuing of new parts in development.  Because the game actually employs an animation that follows the actual processes which cells go through to make a particular vesicle or organelle, there is often a delay between the time the user clicks the button asking for a part to be produced and the time it actually becomes available.  This would not necessarily be a problem, however because the animations are so small and difficult to track, it's not always clear just what the cell is in the process of building and how much longer it will take before a part is ready for action.  There is a simple tracker on the left hand side of the screen that tells players how many components are built and how many are waiting to be built, but a countdown timer would also have been nice, especially in later levels where players might want an extended queue for organelles that make more than one vital component.

Abstract art? No, just a crazy glitch.
The graphics in the cell simulation part of the game contribute to the educational value of game.  Most look like they were plucked straight out of a biology textbook and are presumably fairly accurate models or representations of the piece they represent.  Again, this makes CellCraft seem and excellent game for reviewing cell structures, as anyone who has seen scientific illustrations will be able to understand the art style.  Unfortunately, animations in the cell simulation part of the game are somewhat unreliable.  I encountered a glitch in which my cell membrane went crazy.**  Key organelles were floating around outside the cell's boundaries while the wall twitched and spasmed wildly until I finally failed the objective of the level.

The game also includes an encyclopedia, which juxtaposes information about the various components and organelles as presented in the game, and as they function in the real world.  I thought this was a nice touch, and while players are not ever forced to consult the encyclopedia, they very well may if they happened to gloss over one of the in-game descriptions and need a quick review.  My only complaint about the encyclopedia is that the image area was small, and the scientific explanations were often rather complex. This made the whole experience of reading the encyclopedia slightly cumbersome, and again gave me the feeling that this game was intended to supplement a biology textbook, not stand on its own as an introduction to cell biology.

The only place where CellCraft seemed to truly miss the mark with respect to the educational content is in the overall storyline.  The plot that is introduced to players mostly through short cut-scenes presented between levels is very cute and mostly harmless, but it does make the game convey mixed messages.  While there's great adherence to known fact about cell biology in the simulation parts of the game, the plot centers on a race of sentient platypus-people living on the planet Monotremus who need to save their species from the threat of extinction due to an impending collision with a meteor.  To do this, the platypus scientists decide to splice platypus DNA into the nuclei of amoebas, send the amoebas off to E4R1H (Earth) in a rocket ship, and then using an unexplained scientific device, extract the DNA and make baby platypus clones on this new world.  It's fanciful in an endearing way, but it also feels a little out of place in a game that works hard to make the reality of cell biology a topic of fascination itself.  The graphics and animations in the story/cutscene parts are also in marked contrast to the textbook-style animation of the action in the cell.  While the animations here are definitely more imaginative and fun, the cutesiness of the platypus people again just does not seem to fit with the depth and complexity of the biological material presented here.  The platypus people might be at home in a game that targets players in the 4-8 age range, whereas the biology material looks better suited to a middle or high school curriculum (12-18).
The strange sci-fi plot somewhat undermines the dedication to factual details in other areas.


CellCraft raises the bar for educational Flash games, although it stumbles in several areas.  The game is rather short if you compare it to other online Flash tower defense games like Gemcraft or Protector, and the play mechanics are not deep enough to encourage repeated play.  The game mechanics are draw on popular game styles like tower defense and strategy/sim titles and replicate those at a level that is enjoyable enough, but still not quite as enjoyable as its counterparts in the world of casual games for pure entertainment.  This, however, is not the fault of the biology, but rather from a lack of attention to game balance and pacing.  CellCraft needs a bit more time in QA testing before it can really compete with any of todays more popular casual game titles.

Despite the criticisms I have of CellCraft, I applaud CellCraft for taking up the challenge of making an educational game that is as enjoyable to play as many of its counterparts in the world of pure entertainment.  Given also that the game was made by a very small crew with a limited budget, the results are both impressive and promising as far as the future of educational Flash games goes.  CellCraft shows a laudable commitment to a fairly accurate portrayal of high level cell biology, and for whatever missteps in balance and glitches, the fact that the game has been made freely available and that the code is OpenSource more than makes up for any of its flaws.  Players and developers now have the opportunity to take what CellCraft has done and improve upon it.  CellCraft may not be perfect now, but the game is certainly a step in the right direction: a challenging and informative educational game with creative and satisfying gameplay mechanics.

Pros: Really gets into the details of cell biology, engaging gameplay

Cons: Storyline somewhat ill-suited educational content, irregular pacing, tutorials misleading, glitches

Score: B-

*The mouse scroll wheel can be used to control zoom, which is much faster and more easily used during gameplay.  However, I found that when playing the game online in a browser window, the scroll wheel would simultaneously scroll the browser window.
**CellCraft was glitchy in other respects.  The version with the graphical glitch was played in a browser, but I also tested version 1.0.1 for Mac OS X. Although I was able to play the game through, I did get several recurring errors ("TypeError: Error #1009: Cannot access a property or method of a null object reference."), and one error that made the game crash and forced me to restart the game level.  While these errors were not frequently occurring, there is no denying that CellCraft is still a buggy release.

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