Jack Lumber is an excellent game that arrived on iOS last year. It's reminiscient of Fruit Ninja, in that you drag your finger around the screen to chop through wood, though I think it's an improvement on Halfbrick's formula -- it's got a more complex meta game, and the mechanic is a little deeper as well (the action slows down when your finger touches the screen, allowing for different types of cuts and slashes). Jack Lumber is still available on iOS, but just in case you'd rather use a mouse than your finger, the game has just arrived on Steam as well.
The Steam version will work on your Mac, or on PC or Linux as well, and it's SteamPlay-enabled, so if you buy for one platform you own them all. Currently, the game is on sale for just $5.02, and while there's no new content, the game has been re-tweaked to work with a mouse (though it will also work with a stylus if you'd rather do that). Jack Lumber is a great title, so definitely grab it on Steam if you're interested in that, or just give it a look on iOS if you didn't before.
Update: I was wrong -- the game does have a new "Infinitree" mode to play. So go enjoy that!