[Tayab]

Comments should help you out on what I've done below.

pawn Код:

public OnPlayerConnect(playerid)
{
    SetTimer("IncreaseScore",1000*60*5,true); // Set a timer for 5 minutes. It'll be called every 5 minutes and will not stop unless you want to kill it.
}
forward IncreaseScore();
public IncreaseScore()
{
    for(new i = 0; i < MAX_PLAYERS; i++)
    {
        SetPlayerScore(i,GetPlayerScore(i)+10); // get all the players' score and increment it by 10.
        format(string,sizeof(string),"[SERVER]{FF0000}Everyone's score has been increased with {FF8800}%d{FF0000} score.",GetPlayerScore(i)); // making the string to show up in sending client message
        SendClientMessageToAll(0x40FF00FF,string);
    }
    return 1;
}