export door //this in the beginning of sc file

void door() //this runs when player touches our door sector
{
 if(SC_GetItemCount("key item") >= x) 
 //checks if there are more than "x" ammount of item called key item
 {
  //this script runs if player has enough key items

  SC_SetSectorHidden( int id of closed door, 1);
  //this hides closed door sector revealing open door sector and allowing player to walk over it
 
  SC_PlaySound( "location and name of sound effect");
  //plays sound effect, location for file in sfx folder like "world\\thunder" for sund thunder
  //in folder world

  //if you are usimg money for buying acces ofc we want to take money away from player
  //this takes x ammout of key items away from player
  SC_GiveItem("key item",-x);
 }

 else//optional. This runs if player doesn't have enough items
 {
  //you could add here message saying player doesn't have enough money etc
  SC_GameMessage("message goes here");
 }
}