[Kwarde]

pawn Код:

//Above your script:
forward SendLottoMessage();

//In ongamemodeinit of onfilterscriptinit:
SetTimer("SendLottoMessage", 600000, true);

//somewhere...
public SendLottoMessage()
{
    GameTextForAll("~y~Buy an ~r~/lotto~y~!", 5000, 3);
}

Something like this?