What makes a puzzle game stick for a hundred levels

I've installed and deleted dozens of puzzle games. The ones that survive on my phone, like Gridlock Mind, all do a few small things right. First, they let you experiment without punishment — free undo is non-negotiable for me.

Second, they layer rules instead of just adding bigger grids. A new mechanic every dozen levels keeps your brain engaged far longer than raw size ever could. That slow reveal is the whole craft.

Third, no timers. Pressure turns thinking into panic, and panic isn't fun on a commute. The best puzzlers let the board sit while you stare at it.

Finally, a hint system that nudges rather than solves. When I'm stuck, I want a hand up, not the answer handed to me. Get those four things right and I'll happily play a hundred levels.