It uses HTML5’s local storage. It’s not really a cache, your browser won’t randomly delete it. But it will be removed if you fully clear your browser history (depending on browser and settings).

? the trackpad gestures are great imo...

I remember the days when a game was shipped as an entire product, not broken down into pieces to maximize profits

"Why don't they just let me pay a fee to unlock everything at once?"

You know, that used to be called 'buying a game.'