Check out the top sellers in the iPhone App Store and you’ll see dozens of games with names like Tap Zoo, Tiny Tower, Farm Story, Pet Village, Zoo Story, My Cafe, Tiny Farm, My Zoo, Tower Village, My Farm, Zombie Story and Zombie Zoo Pet Village Cafe Story Farm.

What do these games all have in common besides a repetitive naming scheme? They’re all freemium games, which is a term meaning a game that’s free to play, but costs money to enjoy.

I’ve talked about these games before, but they’re not going away, so I’m giving them another look. This particular variety of freemium game is called a “time ...