[13th]

Code:

forward CheckHealth();

public OnGameModeInit()
{
	SetTimer("CheckHealth",1500,true);
}

public CheckHealth()
{
	new Float: PlayerHealth;
	
	for( new playerid; playerid <= GetMaxPlayers(); playerid++ )
	{
	  if( IsPlayerConnected(playerid) )
	  {
			GetPlayerHealth(playerid, PlayerHealth);
			if( PlayerHealth < 20 )
			{
			  TogglePlayerControllable(playerid, false);
			}
	  }
	}
}