This method avoids get_players() - a native which many avoid since it reduces readability.
Code:
maxPlayers = get_maxplayers();
for(new i = 1; i <= maxPlayers; i++)
{
if(is_user_alive(i))
{
continue;
}
set_hudmessage();
show_hudmessage(i, "You happen to be dead. :(");
}