Why am I unable to install some apps? I own an HTC Salsa with Android 2.3.3 (Gingerbread).

The problem is that I can't download apps like Subway Surfers, Temple Run, Candy Crush, etc. The market reports, "your device is incompatible".

Does it mean hardware requirements?

Is there any way I can upgrade my phone to play the above popular games?

Update:

Very useful information from Mr. Buster. But since there is an update on GOOGLE play now, which doesn't allow you to see the incompatible information.

  
Screenshots (click images for larger variants)
It could mean that your phone does not meet either software or hardware requirements, or both.  You could probably spoof the identity of your phone (so that it could be recognized as Samsung Galaxy S4 for example, instead of HTC Salsa), but you can't expect the app to work properly in this case.

So, I would suggest to get an updated / higher-end phone instead.

UPDATE 2013-10-30: If you're really looking into spoofing the model of your phone, check out Market Helper (needs root).