Insight

49 levels with a varying number of puzzles in each, hundreds altogether. thanks to branching progression usually multiple levels are available to tackle and each puzzle within is unlocked immediately, so they can be solved in any order even if they build on each other. doing more than half is often enough to unlock whatever they are connected to, but sometimes solving everything is necessary. mid-level progress is saved, don't have to do every screen in one go. should be a given, but can't be sure these days.

graphics are very minimalistic, good enough for this sort of thing, though dark mode or a few alternate color schemes would be a must. backgrounds change with every few level packs, but I'd be fine with setting something a bit darker permanently if it was an option.