class User {
    public string Name { get; set; }
    public DateTime DateJoined { get; set; }
    public int Score { get; set; }
}

List<User> users = new List<User>();

users.Sort(delegate (string left, string right) {
    return left.Score.CompareTo(right.Score);
});

users.Sort(delegate (string left, string right) {
    return left.DateJoined.CompareTo(right.DateJoined);
});

var top50pcUsersByScore = users.OrderBy(u => u.Score).Take(users.Count / 2);

Public Class Main
    Public Sub SortByLoginTime(accounts As IList(Of UserAccount))
        Array.Sort(accounts, New UserAccountLoginTimeComparer)
    End Sub

    Public Sub SortByScore(accounts As IList(Of UserAccount))
        Array.Sort(accounts, New UserAccountScoreComparer)
    End Sub
End Class

Public Class UserAccount
    Public Property LoginTime As Date
    Public Property Score As Integer
End Class

Public Class UserAccountLoginTimeComparer
    Implements IComparer(Of UserAccount)

    Public Function Compare(x As UserAccount, y As UserAccount) As Integer Implements System.Collections.Generic.IComparer(Of UserAccount).Compare
        Return Date.Compare(x.LoginTime, y.LoginTime)
    End Function
End Class

Public Class UserAccountScoreComparer
    Implements IComparer(Of UserAccount)

    Public Function Compare(x As UserAccount, y As UserAccount) As Integer Implements System.Collections.Generic.IComparer(Of UserAccount).Compare
        Return x.Score - y.Score
    End Function
End Class