Give the game focus
Click or tap once inside the game area, then test a single control shown by the instructions. Keyboard input often goes to the page until the player has focus. If the page scrolls when you press a key, the game may not have received it.
Avoid holding several keys while testing. One input at a time makes the response clear and reduces the chance that a browser shortcut or page action will interfere.
Confirm the expected input
Read the title's in-game instructions. A key that works in another game may do nothing here; some games use arrows, WASD, mouse clicks, touch gestures or a mixture. Do not assume a controller is supported unless the game says so.
For touch, check whether the game needs a tap, drag or swipe and whether the button is large enough to use comfortably. On a small screen, rotation may improve visibility only if the game layout supports landscape.
Check for loading and performance delays
Wait until the game finishes loading before testing controls repeatedly. A delayed response during a stutter may be a performance issue rather than a wrong key. Close resource-heavy tabs, check the connection and try another title to compare.
If controls work in other games on the site, the issue may be specific to this game's current build. A provider update can change input behavior without changes to the catalogue page.
When to report the issue
If one title remains unresponsive, note its exact page URL, your device and browser, the control you tried and what happened. Include whether other games worked. This gives support a focused reproduction rather than a general report that 'games are broken'.
Do not install a random extension or download to fix controls unless you have independently confirmed it is legitimate and necessary. Browser games should not need unexplained software from an unrelated prompt.