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​Ifoundthis blog postby FourBros Studio, an independent app developer, agood read. It sheds a lot of interesting light on the success the firm’s Taptitude game has seen on WP7. As such it is a great example of the revenue opportunities developers can unlock if they manage to create an early hit fora still nascent storefrontlike Windows Marketplace. Moreover, it includes a chart (“Taptitude Players by Device”) that prompted me to take another back-on-the-envelope-styleangle on the continuingguess gameabout Lumia 900 sales.

Assuming that Nokia sold one million Lumia 710s and 800s in Q4 and two million in Q1,the installed base at end-March would have been three million. There were 91 days in Q1, which puts the sales per day at approximately 22,000. Let’s then assume that the installed base has grown linearly, at the same rate, to date. That puts the installed base on March the 16that 2.670 million and on April the 16that 3.354 million – meaning that the avg. installed base for Taptitude’s evaluation period was about 3.012 million. Taptitude’s combined user base for Lumia 710 and 800 was 32,200, i.e. slightly over 1% out of the installed devicebase.

The rate for Lumia 900 is likely to be somewhat higher (given that Taptitude is only available in English, which is a drag in non-English-speaking markets), let’s say 1.5%. Based on this, the 1,900 Taptitude players on Lumia 900 would translate as an installed base of 127,000 devices, accumulated over a period of nine days. That’d be 14,100 devices sold per day, including the launch date that infamously fell on Easter Sunday. Of course, that’s a figure whichrelies heavily on a number of assumptions, especially about Lumia 710’s and 800’s installed base and Taptitude’s uptake rate on Lumia 900. With such a short sales window for Lumia 900, also the exact date of FourBros Studio’s data can make a substantial difference. I assumed the figures were from Monday the 16thsince the blog was published on the following Tuesday.

Nonetheless, a daily sales figure of close to 14,000 devices, distributed through one single carrier, wouldn’t in my view be a bad start. Maintaining that momentum would push the Q2 figure to somewhere near 1.250 million, which would have been 13% ofAT&T’s smartphone salesand 66% of its non-iPhone smartphone sales in Q4. How profitable this start has been is, then,a whole another matter– but at this stage that is secondary. It’s building up the installed basethat both Nokia and Microsoft should focus on for the time being.​