Gaming hardware in today's age is a lot more intricate than it used to be and is way more advanced than it has ever been.
Hardware is the physical components of computers. Stuff like graphics cards (GPUs), processors (CPUs), hard drives, keyboards, power supply units (PSUs), etc, are all examples of computer hardware. Software is the digital components of computers. Code, programs, or in this case, games, are all software.
The input device used for games, the game controller, varies across platforms. Common controllers include gamepads, joysticks, mouse devices, keyboards, the touchscreens of mobile devices, or even a person's body, using a Kinect sensor.
This is a big thing to put into consideration when talking about the physical things needed to play games in the first place. It is needed to even think about playing a game. Without it, you just wouldn't be able to play.