I'm just going to give you guys fair warning, testing is a lot more work than you think it is. Yes, you play the game. But most of the time you're not testing it to try and beat it, you're testing it to try and break it. This means going off and trying things that you probably wouldn't think twice about as a player, but they're things that you'd have to catch because we don't want a case where the user accidentally crashes the game. Some of the bug reports I've seen as a dev are quite extensive, and involve doing things that I wouldn't think of. You don't know how many bugs I've seen that involve pulling a network cable at just the right time, which isn't fun to test or fix.
There's also the formal stuff, like filing bug reports so that the devs can see them and fix them, and once the devs say they're fixed, trying it again to make sure it's fixed.
Then there's automated testing, where the game literally plays itself.
I don't know if you write the scripts or not, depends on the company, I guess.
All in all, it's not a bad job, if that's something you don't mind doing, though.