If I contort the definition of "game" almost unrecognizably, I might call an Accumulator a type of game in which the only mechanic is accumulating some currency. At some point you can use the currency to buy upgrades which allow you to accumulate currency more quickly.
Accumulators were on my mind after I followed a link to a game called CookieClicker (warning: industrial-grade addiction). It's pretty, but basically you just click the cookie to get 1 cookie. You buy things with cookies that allow you get more cookies. Just to give you an idea, there is an achievement for accumulating 10 trillion cookies.
It reminded me of Ian Bogost's Cow Clicker. Cow Clicker was meant to be a satirical commentary about the brainless time sinks the Zyngas of the world put out. It was supposed to throw those types of shallow, addictive mechanics into stark relief, so we as game designers could collectively see the harm we were doing to our audience and our industry.
Instead of triggering high-minded debate about the direction of the industry, Cow Clicker went viral, and had about 50,000 players in less than two months.
Wondering about the popularity of these "games" led me to hypothesize about how different game genres stimulate different brain regions.
Before I even arrived at that thought, I knew that these games were tapping into a deeply rooted neurochemical reward system. It's not even targeting the relatively "low" limbic system--this is hitting in the hindbrain like meth hits the hindbrain.
Normally I avoid accumulators, but I wanted to answer this question, so I clicked the cookie (a lot). I wanted to know:
How do players begin the cycle of addiction?
Progress is addictive, but how do you get a player to engage with the progress in the first place?
What is it about progress that is addictive?
What breaks the cycle of addiction once it starts?
CookieClicker is juicy. That's one aspect of the game that engages interest initially, before the player is invested in the score. It's shiny and incomprehensible in the same way a cartoon is shiny and incomprehensible to a toddler who is watching.
It's easy. There's no skill involved in making the number go up. No learning curve to frustrate you at all--just juice to mesmerize you like a minnow swimming too close to an angler fish.
It's novel. You visit the page you're not only taken by the visuals, but you're amused at the premise--I have to click the cookie to get a cookie? I'll poke it a little. What's the harm?
What I noticed is a cycle that was familiar to me from Diablo and World of WarCraft, both of which I've played, neither of which I played for very long.
In Diablo you uncover unexplored dungeons which feels good for a while, but then you see an enemy. You're not sure what loot they'll drop, but you know it'll probably be useful at least to sell. Holy shit a Stone of Jordan! Wow, let's try this thing on, that's really cool!
Then you get used to have the Stone of Jordan, you think about leaving, but... I mean, there's only a little ways left until the next waypoint. You might as well get there. And, I guess you're almost done with that quest, you might as well finish that before logging off. Oh, there's another quest. Maybe I should do that one too? Holy Shit Godly Plate of the Whale? I thought that was only for hackers! Damn I'm good.
In psychology we call this intermittent rewards. Intermittent rewards are rewards you sometimes get for doing a task. You don't always get them. If you did, then it would be predictable and lose its interest. But if you're not sure when it's coming... then staying just a little longer couldn't hurt, right?
It's a cycle almost identical to the cycle of abuse: Grooming, Petting, Hitting, Petting, Hitting...
Breaking the cycle is just a matter of breaking the chain of petting and hitting. With abuse petting and hitting is literal. In games we mean rewarding and boring the player.
So if we break the chain by stopping rewards, and only supplying predictable boredom, we lose the player, of course.
The interesting thing is that we can also break the chain by stopping boredom with never-ending rewards. Remember, predictable, reliable rewards are boring. They don't provide the chemical drama that the cycle does.
If I had unlimited cookies to buy whatever I wanted with, I might buy a lot of stuff until the excitement of having the stuff wore off, then I'd be done; got bored, moved on.
What happened is that pretty far into the game, the upgrades became so expensive that it would take days to accumulate enough cookies to get even one of them. I got bored and gave up.
Are Accumulators exploitative, or do they just deliver what a player obviously wants on some primitive level?
My gut says that using this knowledge is potentially "evil" in the "Don't Be Evil" sense. This is a big topic that I expanded on in a different article: Infinite Bliss.
What separates an accumulator from games like Diablo or World of WarCraft?
The games use similar mechanisms to accumulators, and I wonder if they aren't just particularly juicy examples of accumulation. If there is a difference I don't think there's a factor that flips the switch from "legitimate game" to "accumulator" (if such a distinction exists). I think it's probably a spectrum that tracks how "accumulator-ish" a game is. I talk more about how game designers might deal with that spectrum in Infinite Bliss.
Juice is important, especially during the first impression.
Novelty can work as a hook.
Get the player involved in whatever activity is "fun" for your game as early as possible. Like in the menu screen if possible.
Ramp up the difficulty very slowly. Give the player success for doing almost nothing at first, and add complexity just as they are getting acclimated to the current challenge. There is probably a sweet spot of player boredom at which to introduce a new mechanic or challenge.
Don't ratchet challenge or reward. As you turn a ratchet, it stops you from turning it back. If you ratchet up either challenges or rewards without ever going back to some baseline the game will feel like a slog. Creating a boom-bust cycle of reward and boredom will keep a player playing. One of the most powerful tools we have for this is intermittent rewards.