A good while ago I wrote about interaction density in video games.
The creation of that piece happened more or less in one session, with previous research on the subject completed on my part over the duration of several months, with the concept having been mentally formed prior to that.
Since then I've deepened my understanding of the topic and hereby will add my findings and further thoughts.
First of all, interaction density is a multi faceted issue that could, if visualized on a graph, which I won't do, go into several dimensions, simply based on momentary player input as well as the systemic depth of interactions the player is theoretically able to engage with.
In addition, there's a differentiation to be made between forced and choice interactions, which would artificially modify that graph to fit on a predefined scale, for a rail like experience, but more on that later.
To exemplify this, the typical MMO hub can be utilized. Here, the player will have a relatively large potential for all sorts of layered and deep interactions, both when engaging with game mechanics as well as other players.
In the latter situation, the possibilities become almost endless, in terms of communication at least, since any topic could be brought up and, if engaged with by the receiving player, a very deep and layered conversation may occur as opposed to the predefined layers of NPC interactions and conversations, even though perusing a weapon shop has a lot of potential to cost the player a lot of her time, under the right circumstances and matching preferences.
Diving deeper into the categorization between directions of interaction density and to shine a brighter light on the definition, a comparison between two rather popular games will be made.
The Hitman franchise has been a staple in the industry for almost two decades and is considered one of the consistently excellent hallmarks of quality and artistic expression mixed with finesse and hilarity of the stealth action game genre.
The developers themselves describe the Hitman series as "puzzle" games, hidden in the chicken costume disguise of a contract killer.
While the player is given a proper toolset and considered to be skilled at his job, the game strictly predefines the possibility space for the player. When faced with the task to complete a contract on a specific target the player will be able to approach the situation in several ways and some sort of situational improvisation is possible, but a lot of the interactions are scripted and acted out, both by behavioral loops and voice actors, who prerecorded their bits, which are triggered upon reaching certain spots on the map during certain times in the NPC's loop.
Newer titles in the franchise have expanded quite drastically in scale and added a lot more visual fidelity and story details, but the essence of the game remains intact. Cooked down to a simple win conditions it would be something like; kill x, use tool y and/or z. Deviation from this formula is impossible. So, while the player is clever enough to lure a tattoo artist with an appointment to work on a drug boss, who also happens to be a target, into a situation where she can poison his drink and dispose of him to assume their role and then dispatch the drug lord with the tattoo artists tool, it would not be possible to break the pipe of the toilet in the bar the tattoo artist is taken care of, to smuggle it into the mansion and then use it to deal with the target, even though this may seem a feasible option, at least based on general logic.
So while the world the player moves through will be beautifully visualized, akin to walking through an oil painting, with lots of scripted story elements to experience and chuckle at, the available methods to deal with any given situation are by definition rather limited, resulting in an confined degree of interaction density, both in combinatorial, as well as moment to moment interaction, even though the potential for creating chaos is a given at any time, but contradictive to the player mandate. Even that would be easily discerned, though, with a general "all alert" trigger situation, resulting in the players demise within a short time due to heaps of unwanted attention, unless equipped with heavy artillery and then, still, this approach is unfavorable towards completing the missions as intended by the developer.
Compared to another very popular title of Scandinavian origin, Minecraft, Hitman is therefore a pretty to look at funny puzzle, that will never stray too far from its base formula and while letting the player walk through a gorgeous landscape, she can't really touch that many things or - drop any other than the designated chandelier on the target.
The most popular game on the planet, according to newer estimates that even gives Tetris a run for its money, Minecraft is a treasure trove of interactions. All of this is not to say that, again, higher interaction density will always result in a strictly better product, specially considering some newer art piece games, that aim to take the player on a limited, emotionally impactful journey.
Yet, when looking at the game, everything except the skybox is interactive. Everything the player can walk on or into, she can also hit with a pickaxe to utilize as a resource, to then create a pyramid, a virtual Nintendo Game Boy game to be played within the game, a music synthesizer, a castle or a highway spiraling into the sky. Generally, any object the player is able to imagine, she can create a visual representation of, that will often also be a functional object. With additional players the possibility space obviously expands exponentially, if solely based on the fact that an eternal back and forth of removing and adding back a brick is a theoretical option.
Here, the moment to moment interaction density is relatively limited, as long as creeper NPC's and other players don't come into play, with the monotonous resource gathering and similarly monotonous creation of a structure not requiring quick reflexes of any sort. Going into the menu on the other hand, will give ample possibilities for the player to get lost within its depths, considerations towards the fact that whole wiki sections regarding the acquisition and use of building materials, their potential functionalities and combinatorial options have been created by the player base, with the developers not only not helping, but realistically ignoring the effort, have to be made.
Possibilities that allow for the creation of a functioning TV within the game require drastic and sustained effort from the player, if the game is consumed in the traditional manner and no resource hack is used, creating a higher difficulty curve for this type of gameplay approach. Of course, building sandcastles on a virtually created beach also works, as long as that beach has been previously made by either the player or the game's random map generator.
As a generalization, higher interaction density on a systemic level will create bigger potential for sustained player engagement, as long as object creation or character modification is involved, while moment to moment high level interaction density would be what most people consider a "difficult" game.
A great example for that type of game would be the indie darling Cuphead, by many considered a hardcore experience, even on the standard difficulty setting.
Systemic depth isn't really a factor in Cuphead, with very light RPG elements implemented in the form of interchangeable items and weapons the player can equip to best fit any given boss or situation, resulting in very little time spent configuring anything and the overwhelming majority of time used to dodge bullets and shoot their own projectiles at primarily bosses, who exhibit predefined behavioral patterns, that will shift between phases and throw new patterns at the player to be memorized and deal with.
At any given time the player will have to keep track of up to several dozen moving objects on the screen while also repositioning herself and maybe shifting between objects or weapons and firing while aiming to succeed. This creates a tense experience, that will, under the right conditions induce stress in the player and create a correspondingly large endorphin rush when mastered. This is even stronger emphasized through the required pattern recognition of the changing boss phases, often resulting in the need for extensive repetition before any progress can be made.
Switching the virtual 2d needle in the other direction, then, would be something like the Civilization series by Sid Meier, where the player is able to deeply strategize and plan ahead on a macro level, making moment to moment decisions as well, but never with the precondition of any of this happening within a limited timeframe. Essentially, when playing single player, the user would be able to wait to complete a turn for almost a lifetime, assuming no crashes, power outages or deleted files within the game occur.
Object creation taking place in the shape of armies and territories allows for deeply varied choices, from the general approach to war, economics, religion and so on, with all these choices changing the experience within the framework. So can, for example, a pacifistically inclined nation hardly engage in aggressive territorial conquering and will have to default to assimilation of border states through diplomacy and friendship, but will be able to complete trades based on different factors that could be virtually identical to any warmongering nations statistics.
There's more choices to be made in these two games than in virtually any match 3 game, pointing back at the notion that higher interaction density would automatically result in greater popularity.
It will, however, greatly influence the general feel and often pacing of the game, with both moment to moment actions and greater, long term decision making processes, specially taking into consideration the existence of the latter, which usually never take place in "casual" games.
Minecraft, while also considered casual, due to the limitations put on both competitive elements as well as gameplay hurdles, would be one exception of the majority, with the exploratory nature of the game offering aforementioned depth in mostly creative endeavors, letting the player roam endlessly, with the idea of most interaction being created by the player themselves, opposed to curated content, the industry standard for game creation, while also offering premade content apart from the default vanilla sandbox mode.
A diverging example of these two varied two dimensional pendulum swings would be a game like Firewatch, a popular game of the newly created genre known as walking simulators. Here the player will embark on a curated journey with limited choices in a scripted story environment, that aims at creating emotional impact and a sense of connectedness between the (male) player character and the player through dialogue choice. Firewatch, possibly arguably an interactive experience with gameplay elements, offers intrinsic value through these emotionally impactful moments and is quite limited both in terms of extended play and replay possibilities, which hasn't detracted from its overall popularity and critical acclaim.
But it offers a great view at the interactive potential within the game space itself, both horizontally and vertically limited, so to speak, and depending on a space outside of the game in the shape of social player interaction, media coverage and word of mouth to create sustained demand and goodwill for the title despite a relatively short lived gameplay experience. Not to say that any game should offer endless amounts of free playtime to be successful, that would be an economic discussion towards which another entire blog post could be dedicated, but the memory of arcade style "rail" shooters could be brought up in comparison.
A classic from the era of socially interactive player spaces that required carrying heavy amounts of coinage for sustained fun, the rail shooter is a great example for a type of game that has a very predefined set of possibilities with very little possible variation outside of a possibility set of moment to moment interactions to be executed on a pre-constructed path through the game. Rail shooters, though, are a type of game that offer relatively high moment to moment interaction density, one of the reasons for the necessity to bring large amounts of coins to the arcade and stack them up on the side of the cabinet, for quicker access.
One of the classics of the genre could be completed in maybe 30 to 40 minutes of sustained gameplay and required frequent coin reloading in addition to the quick movements of reloading the light gun attached to the machine, by pulling the trigger outside of the frame of the box. Some people are even known to have spent as much as 30 pounds on completing the game, and that's 1990's money, pre inflation.
Another great way to describe interaction density is by looking at a skill tree for the game Path of Exile, seen above. Just by skimming this skill tree, one can easily get an idea of the potential for temporal expenditure figuring stuff out on this spreadsheet, that would then consequently create interactive modifiers within the real time portion of the game, creating a highly complex mesh between real time and deep interactions.
In the case of deep or non moment to moment interaction density a sense of complexity is often created due to a sense of large amounts of interconnected nodes, that each independently would influence moment to moment gameplay when activated, just in terms of visualization, this sheet would be a lot less dense if all the nodes were represented in a straight line. But the number of combinatorial variations to create a freeform character build is quite astronomical, with some nodes creating bigger impact than others. Character build optimization comes into play at this point, apparently rectifying the necessity for supportive explanatory content creation like wiki pages, helping the player in finding the best way to maximize efficiency while playing, which is a determining factor in gauging their enjoyment of the game for a considerable amount of players.
A prime specimen to further exemplify the gradual increase in interaction density in recently popular games is the young genre of Battle Royale's, with the classic PlayerUnknown's Battlegrounds or PUBG for short, with a fascinating origin story as the creation of a young Irish game modder, Brendan Greene, who wanted to make something as an alternative to conventional online multiplayer shooters, primarily for his friends, and the corporately backed incumbent Fortnite, taking the world by storm.
Apart from artistically stylistic differences and a slightly more mature approach from PUBG, cast iron skillets to protect ones buttocks not counted, the main differentiator with Fornite is the fact that players, while running around an increasingly tighter space that shrinks as a result of an energy bubble constantly decreasing in size and squishing anyone outside of its life giving aura within seconds, also have to build constructions like ladders or wooden sheds to navigate the environment and protect themselves from competitively fired projectiles, resulting in a much more frantic experience and requiring highly acute reflexes and split second planning capabilities, opposed to the slightly calmer and more strategic PUBG approach.
In summation: Interaction Density plays a major role when choosing what type of game to create and who to create it for. From the perspectives of depth in terms of potential longevity, sustained play through player creation, variability, replay value by offering similar yet sufficiently diverging experiences, as well as adrenalin rush inducing hectic situations and anything in between. Again, even walking simulators have interaction density, they're just a lot less dense than shmups.