Just six weeks ago, Draw Something was the hottest mobile game in the world, but today its popularity has collapsed and Zynga may be left holding the bag.

Online game company OMGPOP launched Draw Something on February 6 of this year and watched it soar to 35 million downloads in just seven weeks. Not since the runaway sensation Angry Birds, had a game became the favorite pastime of iPhone addicts so quickly. That's when Zynga, the mobile game company that's intimately linked with Facebook, pounced. They quickly snatched up OMGPOP and its 40 or so employees for $200 million, rescuing a struggling company that had burned through $17 million in funding in six years and was on the verge of bankruptcy before stumbling upon the Pictionary clone that made everyone rich.

It was a great story ... for OMGPOP. For Zynga, it's starting to look like an expensive blunder. The company's earnings report last week appeared to be decent enough, showing strong revenue numbers that beat expectations. So why has Zynga's stock price declined by almost 50 percent since the beginning of March? Why has the acquisition of such a red-hot property not made investors happy? Because the hottest game in town, isn't so hot anymore. 

Two weeks ago, Business Insider checked in on the number of people still playing Draw Something and noticed a disturbing downward trend. Way downward. As of May 1, it's gotten even worse, with the average number of users per day is now below where it was when Zynga acquired the game. (It's currently around 10 million, down from a peak of close to 15 million.) Monthly users — those causal gamers who play occasionally, but not fanatically — had been pretty steady, but now even that number is starting to drop. It's clear that fewer people are drawing things and doing it less often. Like most one-hit wonders, fans got bored and moved on.

Note: AppData numbers are based on Facebook logins, which are popular but not required for the game. Still, the trend is obvious.

Most interesting of all though, seems to be fortuitous timing (from OMGPOP's perspective) of the sale to Zynga. As Forbes' Tero Kuittinen noted, the game's popularity peaked almost exactly on the day that the company was bought. At the time, Draw Something looked like the next Angry Birds, but whereas that game (with its upgradeable levels and expanding challenges) has stayed at the top of the charts for more than year now, Draw Something has collapsed almost quickly as it peaked. It's even been replaced by a newer version of Angry Birds. And investors have noticed.

For OMGPOP, the sale could not have been timed more perfectly. Had Zynga not stepped in, the company would be out of money right now, and frankly, few people would have missed it or its game. Instead, it's Zynga's management, which has seen its stock price struggle since its IPO late last year, that has to wonder where it all went wrong.