They did three very important things (that we are trying to do now in our relaunch): They removed unnecessary and less-used features, such as picking opponents, setting up challenge mode games, selecting a dictionary, etc. Next, they had a smooth, top-notch interface that made it a breeze starting games and ensuring the learning curve was small. Finally, they had all the tools required for a viral effect, i.e., multiple sharing options, ability to start games with people on the contact list, etc. All combined, it was a winning formula.