[zrgiu_]

remember that you paid $4.64, but 30% of that went to Amazon anyway. Generally, about 2-3% of the people who would download a free app would also pay for it, which could make Underground a good choice. People who haven't paid though, aren't as invested, and are more likely to quit using that app sooner.

Also, there's the niche issue: it's very possible that fighting fantasy fans are more likely to pay for their apps, which means none of these numbers applies to them.