By nature, we humans are not easily content with our circumstances. By some perverse force within us, the moment we possess something or get what we want, our minds begin to drift toward something new and different, to imagine we can have better. The more distant and unattainable this new object, the greater is our desire to have it. We can call this the grass-is-always-greener syndrome. The psychological equivalent of an optical illusion, if we get too close to the grass, to that new object, we see that it is not really so green after all.
Stacks and Trees quickly see that certain levels you reach, the seriousness of the game outweighs the fun. Friends and close companions become venomous snakes concealed in tall grass in the blink of an eye. One thing about the streets is your path is dark, which means you will never know what you trip over.