Keypad as game input device?

I did a post about keypad handlers. I'm reluctant to mention it because we aren't supposed to post "link only" answers.

It refers to a library available on GitHub which handles keypads. In particular you can have a callback function for both the keydown and the keyup, for multiple keys.

How do i use the Keypad.h library to get my keypad press to run one line of code when i press a button and another line when i release the button.

That seems to be what you want to do.

Example code:

/*
 * 
 * Example of using Keypad_Matrix with a 4x4 keypad matrix.
 * 
 */

#include <Keypad_Matrix.h>

const byte ROWS = 4;
const byte COLS = 4;

// how the keypad has its keys laid out
const char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'},
};

const byte rowPins[ROWS] = {6, 7, 8, 9}; //connect to the row pinouts of the keypad
const byte colPins[COLS] = {2, 3, 4, 5}; //connect to the column pinouts of the keypad

  // Create the Keypad
Keypad_Matrix kpd = Keypad_Matrix( makeKeymap (keys), rowPins, colPins, ROWS, COLS );

void keyDown (const char which)
  {
  Serial.print (F("Key down: "));
  Serial.println (which);
  }

void setup() 
{
  Serial.begin (115200);
  Serial.println ("Starting.");
  kpd.begin ();
  kpd.setKeyDownHandler (keyDown);
}

void loop() 
{
  kpd.scan ();
  // do other stuff here
}

You can also use setKeyUpHandler to do another function when a key is released. You can also call isKeyDown to see if a key is down (eg. when pressing key A is key B also down?).

Note that (as mentioned in the linked post) you need to use diodes to stop having false (ghost) key presses if more than two keys are pressed at once.

How do i use the Keypad.h library to get my keypad press to run one line of code when i press a button and another line when i release the button

Edit 1:

void loop() {
  char key = keypad.getKey();

  if (key != NO_KEY) {
    Serial.println(key);
  }

  if (keypad.isPressed('*'))
  {
  randomr = random(10, 2000);
  Serial.println(randomr);
  }

}

From the link: https://playground.arduino.cc/Code/Keypad/ you can find all the functions supported by the Keypad library.

One relevant function is

KeyState getState()

It returns the current state of any of the keys. The four states supported are IDLE, PRESSED, RELEASED, and HOLD.

Hence you can use this function for the keys you are interested in.
Also, if helpful consider this function as well.

setHoldTime(unsigned int time)

Set the number of milliseconds the user will have to hold a button until the HOLD state is triggered.

You can find the keypad.h library in action here. I motivate you to also try the code with this online Arduino emulator

you already have a builtin function defined to get the status of the key pressed

void loop() {
  char key = keypad.getKey();

  if (key != NO_KEY) {
    Serial.println(key);
  }
}

I have a poorly taken screenshot for the same for your quick reference.

Original Arduino emulator link: (you can play with the logic)

https://wokwi.com/playground/keypad

Disclosure: I use wokwi.com, to create interesting tools and libraries for the Arduino community 🤟 https://github.com/wokwi

for a more free demonstration of the libraries:
https://github.com/wokwi/arduino-libraries