By default, an Android application requires the feature android.hardware.touchscreen, which is then used for filtering in Google Play, so only devices, that have touchscreen capabilities, will be able to install that app.

Besides that, there is a more basic feature, android.hardware.faketouch; android docs state:

If your application requires basic point and click interaction (in other words, it won’t work with only a d-pad controller), you should declare this feature. Because this is the minimum level of touch interaction, your app will also be compatible with devices that offer more complex touch interfaces.

If the application does not require touchscreen features, it is recommended to set android.hardware.touchscreen to not be required, but declare android.hardware.faketouch instead, so I did this for WordMix, which should work with faketouch devices, too:

<uses-feature android:name="android.hardware.touchscreen" android:required="false" />
<uses-feature android:name="android.hardware.faketouch" android:required="true" />

If you do that, check the results on Google Play, which shows the number of supported devices:

• touchscreen required, faketouch not required: 1500
• touchscreen not required, faketouch required: 860
• neither required: 1800

That is odd and not according to the documentation. For example a Samsung GT-S5360 seems to support touchscreen, but not faketouch. The Samsung Galaxy S2 supports both. You can include all devices by setting touchscreen to be not required, which then includes all faketouch devices, but also all devices that have even less input capabilities.