Check that the game has a mapping
Look for a controller icon, a settings panel, or a control list that names gamepad inputs. If the page only documents keyboard or touch, do not assume a controller will work because the browser supports gamepads. MDN describes the Gamepad API as a way for developers to respond to connected controllers and read their button and axis state; game-level support still needs implementation.
Controller layouts are not universal. MDN's gamepad tutorial cautions that button arrays can differ across devices, and an unknown mapping may not use the standard layout. Test movement, confirm or jump, pause, menu navigation, and any analog trigger with your own pad. Check whether prompts show the button name a player will actually see.
Test focus, connection and return paths
Connect the controller before loading the game, then try connecting it after the page is open. Click the play area if the game requires focus, and check whether a browser or operating-system prompt appears. Pause, unplug the controller, reconnect, and verify that the game returns to a usable state rather than keeping a stale input or leaving the player stuck.
Try one keyboard control too, especially for menus and recovery. A controller can be comfortable for movement while a mouse remains easier for text entry or settings. If you need a specific feature such as vibration, do not infer it from ordinary button support; verify that the game and environment explicitly provide it.
Choose a supported setup
If controller play is essential, start from a game page that clearly lists gamepad controls or a platform directory with a controller input filter. Run a brief test before a long session. If no input guide exists, ask the publisher for the supported devices rather than installing a browser extension that requests broad access just to remap buttons.
Questions about controller support in browser games
Does the browser's Gamepad API mean any web game supports controllers?
No. The API gives game developers access to connected controller inputs; the game must implement and map those inputs. Check the game's own instructions.
Why do controller prompts show different buttons?
Controller layouts and mappings can differ by device. A title may assume one mapping or show generic labels, so test the pad and read its in-game control guide.