code:

const int pinLeftUp = 2;
const int pinLeftDown = 3;
const int pinRightUp = 23;
const int pinRightDown = 22;
 
void setup()
{
  Serial.begin(57600);
  Serial.println("BEGIN:");
  pinMode( pinLeftUp, INPUT_PULLUP );
  pinMode( pinLeftDown, INPUT_PULLUP );
  pinMode( pinRightUp, INPUT_PULLUP );
  pinMode( pinRightDown, INPUT_PULLUP );
}
 
void loop()
{
  if (digitalRead(pinLeftUp) == LOW){ Keyboard.set_key1 (KEY_W); }
  if (digitalRead(pinLeftDown) == LOW){ Keyboard.set_key2 (KEY_S); }
  if (digitalRead(pinRightUp) == LOW){ Keyboard.set_key3 (KEY_R); }
  if (digitalRead(pinRightDown) == LOW){ Keyboard.set_key4 (KEY_D); }
  Keyboard.send_now();
  delayMicroseconds(10);
}