One who test games, can they test software too? or they need any special requirements for software testing?
I'm going to start with my standard response: it depends.
I'm assuming you're talking about computer games and not board or other kinds of games, but the computer game industry has something of a reputation for using a lot of unskilled testers. That reputation comes from the fact that the large game development companies can call on gamers who think it would be cool to get their hands on the new hot game before anyone else (and some of them would do it free). That pool burns out fast but gets cycled quickly, too. Someone whose only games testing experience is from this group is going to be out of their depth in most commercial applications testing.
On the flip side, the skilled testers in the game industry would have no difficulty moving to commercial applications. They'd need to become familiar with the application domain but beyond that, there wouldn't be a problem.
Tester role requires some degree of creativity, ability to spot the things and learn-ability.
Those who are testing games do have these qualities. Question comes to understanding and adapting tools and process used in software testing.
I guess it is matter of adapting and learning tools and processs for person who is in game testing.
Game is software actually. Testing process is still same in common for any software product for selected workflow. Game testing has own features but it still software testing as far as I know. Each software product requires some special knowledge which you can get during work. So, answer on your question is YES, test engineer who understand development life-cycle, testing process would not get any hard problems in software testing.