new
    AlmostDead [ MAX_PLAYERS ] = 0; // Create this player variable on the top of the script.

public OnPlayerUpdate ( playerid )
{
    if( AlmostDead [ playerid ] == 1 ) return true;
    
    new
        Float: health;

    GetPlayerHealth ( playerid, health );

    if( health <= 5.0 )
    {
        ApplyAnimation ( playerid, "CRACK", "crckdeth2", 4.0, 1, 0, 0, 0, 0 );
        ApplyAnimation ( playerid, "CRACK", "crckdeth2", 4.0, 1, 0, 0, 0, 0 );
        // Apply the animation twice so it works without preloading.

        TogglePlayerControllable ( playerid, false );
        // This is optional - warning, it makes them invincible if they can't control their character.
        
        AlmostDead [ playerid ] = 1;
    }
    return true;
}