We are not very fond of feature less Apple Safari web browser and prefer using Chrome over it. Unfortunately when we open links from any application or games, they all open in Safari as there is no option to change the default web browser.
However if you are ready to jailbreak your iPhone, there is a utility called Browser Changer that tells any application to open that particular link the web browser of your choice. So your links will open in Chrome, Opera or any other browser.
Browser Changer allows you to make third party web browsers your default. It can also redirect map links to open in the Google Maps app. Browsers can be selected in the Settings.app