QA need a plan for how to test the game. If they have no plan to follow they are people playing at random and not a functional QA team.
Type of Test
The type of a test is what the test focus on and how it is done.
Functional testing check that the game works like it is designed to.
This is tests the user interface and the mechanics of the game. How well does new players understand it and how fast does it take to learn how to play.
Are there people that think this game is fun, how many are they and would they pay for it.
This type of testing verify that the game follows the rules set by the platform or online shop it will be released from.
This tests try to break the game by doing stupid things with the hardware or the game itself. Try to play without soundcard, pull the network cable in multi-player or try to play the flightsim with a tac-2, 'but it's a joystick it should work'.
This type of testing try out the possible hardware the game can run on. On PC there are many types of configurations and on console very few. This type of testing also try to find the minimum configuration for the game and performance testing.
This is testing without any plan. Normally this is pointless as without structure the testers will simply derp around and waste time. I can be useful from time to time as things can be missing in the test plan. Random testing like this might catch such things.