Universal Paperclips is incredibly engaging for a game about producing paperclips. There are a number of aspects of Universal Paperclips that make it as effective and engaging as it is and I will try to mention a two and what this can teach us about elements of engaging video games.
Immediate and Constant Feedback
Universal Paperclips opens with the play clicking a button to produce paperclips. From the beginning, it seems arbitrary. Paperclips don't matter. The player shouldn't care. But the number has a magical feeling. Watching the number go up: your actions directly producing a result and advancing you feels good. It provides an immediate feedback as you see a number increasing. A number which is an immediate reward for your efforts. This number on it's own isn't engaging, but it's the ability to look back on where you were and immediately see yourself moving forward that makes even this clicking so engaging.
Then, later in the game, every millisecond there's feedback. You see your paperclips increasing every second and your income increasing and your operations and creativity increasing. Your eyes are overwhelmed with feedback, gluing them to the screen for more. This constant, unyielding stream of feedback further compounds the effect.
Unpredictability and Exponential Progression
What keeps the player playing is the prospect of seeing the numbers go up. However, if the game was only to click the button to produce paperclips it wouldn't be nearly as engaging. In Universal Paperclips, the player can't predict how many clips they will be producing in the even 5 minutes. There are spikes that always seem to be just within our grasp, which will make all the effort they're currently put in so far meaningless since it will be able to be done in minutes if not seconds.
These power spikes make every minute playing the game count and make them reluctant to put down the game. Other games have elements like this but Universal Paperclips uses the exponential progression of production to produce the unpredictability and make the player want to play those last few minutes. The marginal benefit always seems so incredible and so putting the game down is not worth it.
I'm very curious if you guys noticed any other interesting aspects of video game design that universal paperclips points towards that can teach us about what makes a game engaging.