In addition to the unique gameplay, I really appreciate the amazing design sense that clearly went into everything in the game. Every screen is a pleasure to look at.
You should definitely be able to navigate around the areas with WASD or arrow keys, it's annoying to have to move the mouse back and forth between the square you want to dig at and the dig button.
There are purple stars worth $25 each high up above the jet stream. A good strategy, when your plane is able to do this, is to rocket straight up at the beginning and go up as high as you can, then stall out intentionally and restart your engine by mashing the spacebar. Then just run into purple start on your way down. I got on the leaderboards with this strategy.
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