An easy way to make money is by upgrading Helmet and engine (then later grain to refill), that way you don't get killed and stoped by the birds and you make 300 to 1k coins per launch.
Smelt gets too "fast" after smelt some thousand of ores, but is so fast that flashplayer freeze or smelt stops and you must reset the game to have a chance to smelt something.
Remember: You can always jump in the air after sliding off a platform, that way is easy the first level. Also press space when close to the black "star-cube" to get to the next level. Fun game but short.
I'm compiling a fix for this right now. Edit: and its updated now