Begin with the primary actions. Place them where the intended audience can reach comfortably and where accidental touches are less likely. Consider whether the game is played in portrait or landscape, with one hand or two, and for short or longer sessions.
Observe without coaching
Give the build to someone unfamiliar with it. Watch where their fingers go and what they expect. Are important objects hidden under a thumb? Do they trigger actions accidentally? Does a control require precision that the display does not support comfortably?
Test interruption and movement too. Notifications, orientation changes, app switching, and pauses can affect the session. A stable desktop build does not prove that the touch experience and lifecycle behavior are correct on a device.
Define the supported test set
Choose representative devices based on the audience and scope. Record what was actually tested and what remains unverified. Simulators and automated checks can help development, but they do not establish physical-device acceptance.
Use the findings to adjust layout, feedback, sensitivity, and control options. The goal is a comfortable relationship between the player's intent and the game's response. A mobile control system should be judged while people use it, not solely from its appearance in the editor.