No Reward Is Not a Small Reward
Candles stopped doing anything once the cake was full, and my first fix raised the goal. What needed fixing was the distance between action and response.
When HappyBirthTown was still a pixel party that ran for one birthday, there was a cake in the middle of the plaza. Guests wandered the town picking up candles and pushing them into it. Each candle filled the cake a little more, and that was a reason to keep moving around the party.
The trouble started once the cake was full. After that, no matter how many candles went in, the screen did not change. The reason to go looking for candles vanished halfway through the party. I fixed this twice in one day. The first answer was half right. Only with the second did I see what I had been misreading.
A second place instead of a bigger bowl
The two easiest answers arrived first, and both were traps. One was to add more slots. The cake would disappear under candles, and with it the flavour the host had chosen. The same wall would stand again a little later, and by then the cake would be gone too. The other was to empty the cake when it filled and start again. But when a trace people left gets undone, that is not a celebration. It is a reset.
So I neither enlarged the bowl nor emptied it. I made a new place beside it. Once the cake filled, candles spilled out onto the plaza and stood in rings around it, a wreath. What I liked about this was that it enlarged a climax the party already had. At the time there was a moment when everyone blew out the candles together, and the bigger the wreath, the wider the blackout and the longer the flame took to spread. I added no gauge and no "this many left". The picture was the progress.
When progress hits a ceiling, the instinct is to raise the limit. That only moves the wall back, and it usually knocks down the reason the limit was set where it was. Here that reason was "the cake has to look like a cake". Letting what has been filled become material for the next stage still seems right to me.
"You just did arithmetic"
Feedback came back the same day: the number of candles had grown far too much; I had simply done arithmetic. It was accurate.
The original problem was "once the cake is full, adding a candle produces no response". My answer made people collect a dozen more candles before the next thing happened. Nothing responded until a ring of the wreath was complete. I had turned a silence that came every twenty minutes into one that came every thirty, and called it fixed. The gap between silences grew. The silence itself was untouched.
Looking back, I had misread the problem. I read "there is no reward" as "the reward is too small", and so I went towards making the reward bigger: a bigger goal, a bigger wreath, a bigger climax. But what guests were feeling was not the size of a reward. It was its absence. Pushing a candle in made nothing happen.
The fix was distance, not size
The second answer left the goal alone. The rings of the wreath stayed as they were, and every action got a response of its own. After the cake had filled once, each candle set off a small celebration, and its line named how many candles we had gathered so far.
There were five lines, rotated by that count. Picked at random, different people would get different celebrations, and the sense of "our cake" would break. A single line would read as a counter rather than a celebration. Completing a ring stayed the bigger moment, and at that moment the small celebration stepped aside, because two at once blur each other.
With that change, an open question disappeared too: "what happens after the wreath is full?" When the distance between action and response is zero, no stretch on the way to the goal is empty, however far away the goal is. The goal can be large. The problem had never been its size. It was the silence in between.
Keep both answers
The two decisions do not cancel each other. The first was right about the goal. Making a new place rather than a bigger bowl kept the cake a cake, and tied the collecting to a climax still to come. The second was right about the reward. The further away that goal sat, the more each action needed something answering it at once.
When people say "this isn't fun anymore" at a point where progress stalls, it is easy to hear "give me something bigger". Since this, I ask a different question first: how far apart are the thing this person just did and the first moment the product answers it? That distance has usually been the thing to fix before the size.