public OnGameModeInit()
{
    // We're creating a sniper-based gamemode now, so we don't want players to
    // see any nametags. Fully disable them:
    ShowNameTags(0);
}

new bool:Masked[MAX_PLAYERS] = false;
new OldName[MAX_PLAYER_NAME][MAX_PLAYERS];

CMD:mask(playerid, params[])
{
    if(IsPlayerConnected(playerid))
    {
        if(Masked[playerid] == false)
        {
            new pname[24];
            GetPlayerName(playerid, pname, sizeof(pname));
            Masked[playerid] = true;
            strmid(OldName[playerid], pname, 0, strlen(pname), 64);
            SetPlayerName(playerid, "The Stranger");
            SendClientMessage(playerid, COLOR_GREEN, "* You have put on your mask.");
            for(new i=0;i<MAX_PLAYERS;i++)
            {
                ShowPlayerNameTagForPlayer(i, playerid, 0);
            }
        }
        else
        {
            SetPlayerName(playerid, OldName[playerid]);
            Masked[playerid] = false;
            SendClientMessage(playerid, COLOR_GREEN, "* You have removed your mask.");
            for(new i=0;i<MAX_PLAYERS;i++)
            {
                ShowPlayerNameTagForPlayer(i, playerid, 1);
            }
        }
    }
    return 1;
}