GetKey
If you want to get a keyboard key press that is not assigned to an axis, you can use GetKey(), GetKeyDown(), or GetKeyUp() to reference keyboard keys via their KeyCode.
The GetKey() functions work pretty similar to the GetButton() functions. GetKey() returns true while the key is being held down; GetKeyDown() returns true only once, on the frame that the key is initially pressed; and GetKeyUp() returns true only once, on the frame that the key is released.
Each key has its own KeyCode that needs to be referenced in the parentheses of the GetKey() functions. You can find a list of all the keyboard KeyCodes at https://docs.unity3d.com/ScriptReference/KeyCode.html.
So, for example, if you wanted to check whether the 8 key from the alphanumeric ...