Tips & Tricks
Most mobile platforms recommend you only install apps from approved sources to protect your security, and Windows 8 is the same: it’ll only allow you to install trusted (that is, digitally signed) apps from the Windows store.
If this proves a problem, though, and you’re willing to take the security risk (because this isn’t something to try unless you’re entirely sure it’s safe), then the system can be configured to run trusted apps from any source.
It’s all done via a single Registry key, too. Just launch REGEDIT and set the value of the HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Appx\AllowAllTrustedApps key to 1.