Most of the development, on the first two versions for the PC and Wii at least, was done by two people. Pretty impressive.
They've also done Little Inferno which is awesome. On paper it really shouldn't work lol. You've got a bloomin great big furnace and a box of matches. So you burn the leaflet that came with it and you get money for doing it. So you order stuff from a catalogue and burn it and get more cash. There are also puzzles in the form of combos, burn the right combination of stuff and you unlock stuff like extra catalogues to order from.
It doesn't sound great but once you start playing it's very difficult to put down lol.