The game itself seems executed well enough and is playable, but it isn't a well-polished game. It has a lot of potential.
For one thing, the spelling on the instructions page needs to be checked: "happiness"?
For another, the music should have neater looping. Currently it ends, and then starts over very abruptly, instead of smoothly looping.
The graphics are not only lacking, but inconsistent. Your cart, the well, and the dunes in the background are done in three different styles.
When the wind starts blowing, existing raindrops don't start drifting, which is just lazy and doesn't make sense.
The game also lacks a goal, benchmarks to beat/reach, powerups, etc...and the difficulty levels don't introduce anything new, just less rain and more lightning. Overall the replay value is low for repeating a game, and equally low for choosing a different difficulty. Play this game at any difficulty for 10 seconds and you've played it all.