This is what's going on...
That's half a million installs in less than a week. It wasn't available in the US until last Friday, at which time it had <10,000 installs.
For comparison, around 90,000 members played a qualifying round in the Virtual US Open last spring.
9,000 reviews in the Play Store, again in a week. I'm not sure we have that many forum posts in a typical month anymore, and Yankee Jim and Courteney are still around.
The good news is that the mobile version should help keep this creaky old boat afloat a while longer.