Cool! glad to see it on the testing site! Immediate feedback after playing around a little bit - double right click feels weird to me. Why not just single right click to zoom out? Or perhaps -
Click and drag - Pan
Double click - center the screen on the target square at the current zoom level
Alt-left click - Zoom in
Alt-right click - zoom out
Alt + Click is the same as Right Click throughout Shmeppy, so I feel like it would be inconsistent to use Alt + Right Click distinctly from Right Click. My reasoning for doing that is that right clicking can be a bit awkward with some mice. It can be weird with some trackpads and there are plenty of physical mice out there that only have one button, though I don’t know how common they are anymore.
Allowing a single right click to zoom out with a double left click to zoom in might be interesting… it sounds a strange to have the asymmetry, but it might be alright. I was thinking of having every click after the second click trigger a zoom too, rather than every other, so that might make it feel a bit more consistent.
Hmm… I feel like this is going to end up feeling too weird, but probably worth a shot.