Gameplay testing exercises a game through actual play. It can check movement, aiming, reloading, damage, navigation, objectives, difficulty and the feedback shown after player actions.
Testing separates visual quality from functional quality. Realistic characters and maps can coexist with broken mechanics that prevent the experience from behaving as intended.
ELI5
Gameplay testing means playing a game carefully to find what works and what does not. The tester tries important actions instead of only looking at the graphics.
For example, a tester can confirm that aiming points in the expected direction, reloading changes ammunition and taking damage affects the player's state.
What should gameplay testing cover?
It should cover controls, objectives, feedback, collisions, difficulty, progression, failure states and the main player journey.
How is gameplay testing different from visual review?
Visual review judges appearance, while gameplay testing exercises interactions and rules to verify that the experience functions.

