I admit I was indeed using it with a mouse. I tried it on mobile later and... my first intuition was still to tap buttons, not hold them down. I don't like or use trackpads frequently so I can't say much on that.
I'd guess it depends on what you think your readers may be using and how they use it, but my bet is still that it will be confusing to a fair portion of readers.
P.S. In fact, on mobile it's somewhat more confusing, because the actions will trigger when I am scrolling and inadvertently place my finger on something. What happens in this case is that the action won't "reset" when I take my finger off. I know none of this is a critical problem, but it does make it appear confusing or even somewhat broken.
By default, animations start and end "softly", because it's just nicer overall.
For the buttons in question, I updated them so that they have a hard start and a soft end.
The result is that if you reload the page, the animations start much more quickly and it's more obvious what's happening.
The problem with a simple click is that the transformation would be instantaneous, and it wouldn't look very good. Or, I can start the transformation with a click and let it end later — but then I'd need a reset button.
I don't know much about Android, but Apple wanted so badly to offer the "real internet" on the iPhone yhat they overrode lots of default browser events behavior.
Things like mouseup just don't get triggered if the user scrolls first, and scrollevents are sent infrequently.
Don't get me started on pinch to zoom which uses TWO invisible rectangles to show content.
I'd guess it depends on what you think your readers may be using and how they use it, but my bet is still that it will be confusing to a fair portion of readers.
P.S. In fact, on mobile it's somewhat more confusing, because the actions will trigger when I am scrolling and inadvertently place my finger on something. What happens in this case is that the action won't "reset" when I take my finger off. I know none of this is a critical problem, but it does make it appear confusing or even somewhat broken.