Solving problems is good. You can also appeal to people's passions or identity. Addictive also seems to work. If you want to just solve a problem, you gotta un

Solving problems is good. You can also appeal to people's passions or identity. Addictive also seems to work. If you want to just solve a problem, you gotta understand the worst problems people have. Twitter and Facebook work because they have people on there, who others want to follow or friend. Video games appeal to raw passions, and can also be addictive.