It is a standard, but very important stage of the game development, which affects the commercial success. Because if the player is confronted with the bugs in the first hours of the game, it greatly reduces the interest in the game.
It is worth to distinguish the following notions: a gamer and a game tester. The purpose of tester – to find bugs in the program code, which may negatively affect the gameplay. A gamer, on the other hand, is on the other side and interacts with the finished software product. But the gamer’s experience can help the tester a lot, because it allows him to evaluate the game process more deeply.