This is the random number generator we use in HA!  It's a much truer Random than System.Random.  It's slower, but not as slow as the Crypto Random.

Converted from C by Paul Vick, initially for use in Heroic Adventure.  Thanks Paul! 

For more information about the Mersenne Twister and the concepts behind it, I encourage you to read this Wikipedia article.

To save some cut & paste heartache, I've attached the source file to this post. Be sure to grab it:  MersenneTwister.vb

Option Strict On

Private Const N As Integer = 624
Private Const M As Integer = 397
Private Const MATRIX_A As UInteger = &H9908B0DFUI
Private Const UPPER_MASK As UInteger = &H80000000UI
Private Const LOWER_MASK As UInteger = &H7FFFFFFFUI

Private mt(N - 1) As UInteger
Private mti As Integer = N + 1

''' <summary>
''' Create a new Mersenne Twister random number generator.
''' </summary>
Public Sub New()
     Me.New(CUInt(Date.Now.Millisecond))
End Sub

''' <summary>
''' Create a new Mersenne Twister random number generator with a
''' particular seed.
''' </summary>
''' <param name="seed">The seed for the generator.</param>
<CLSCompliant(False)> _
Public Sub New(ByVal seed As UInteger)
     mt(0) = seed
     For mti = 1 To N - 1
          mt(mti) = CUInt((1812433253UL * (mt(mti - 1) Xor (mt(mti - 1) >> 30)) + CUInt(mti)) And &HFFFFFFFFUL)
     Next
End Sub

''' <summary>
''' Create a new Mersenne Twister random number generator with a
''' particular initial key.
''' </summary>
''' <param name="initialKey">The initial key.</param>
<CLSCompliant(False)> _
Public Sub New(ByVal initialKey() As UInteger)
     Me.New(19650218UI)
     Dim i, j, k As Integer
     i = 1 : j = 0
     k = CInt(IIf(N > initialKey.Length, N, initialKey.Length))
     For k = k To 1 Step -1
          mt(i) = CUInt(((mt(i) Xor ((mt(i - 1) Xor (mt(i - 1) >> 30)) * 1664525UL)) + initialKey(j) + CUInt(j)) And &HFFFFFFFFUI)
          i += 1 : j += 1
          If i >= N Then mt(0) = mt(N - 1) : i = 1
          If j >= initialKey.Length Then j = 0
     Next
     For k = N - 1 To 1 Step -1
          mt(i) = CUInt(((mt(i) Xor ((mt(i - 1) Xor (mt(i - 1) >> 30)) * 1566083941UL)) - CUInt(i)) And &HFFFFFFFFUI)
          i += 1
          If i >= N Then mt(0) = mt(N - 1) : i = 1
     Next
     mt(0) = &H80000000UI
End Sub

''' <summary>
''' Generates a random number between 0 and System.UInt32.MaxValue.
''' </summary>
<CLSCompliant(False)> _
Public Function NextUInt32() As UInteger

Dim y As UInteger
Static mag01() As UInteger = {&H0UI, MATRIX_A}
If mti >= N Then
     Dim kk As Integer
     Debug.Assert(mti <> N + 1, "Failed initialization")
     For kk = 0 To N - M - 1
          y = (mt(kk) And UPPER_MASK) Or (mt(kk + 1) And LOWER_MASK)
          mt(kk) = mt(kk + M) Xor (y >> 1) Xor mag01(CInt(y And &H1))
     Next
     For kk = kk To N - 2
          y = (mt(kk) And UPPER_MASK) Or (mt(kk + 1) And LOWER_MASK)
          mt(kk) = mt(kk + (M - N)) Xor (y >> 1) Xor mag01(CInt(y And &H1))
     Next
     y = (mt(N - 1) And UPPER_MASK) Or (mt(0) And LOWER_MASK)
     mt(N - 1) = mt(M - 1) Xor (y >> 1) Xor mag01(CInt(y And &H1))
     mti = 0
End If
y = mt(mti)
mti += 1

' Tempering
y = y Xor (y >> 11)
y = y Xor ((y << 7) And &H9D2C5680UI)
y = y Xor ((y << 15) And &HEFC60000UI)
y = y Xor (y >> 18)
Return y

End Function

''' <summary>
''' Generates a random integer between 0 and System.Int32.MaxValue.
''' </summary>
Public Function [Next]() As Integer
     Return CInt(NextUInt32() >> 1)
End Function

''' <summary>
''' Generates a random integer between 0 and maxValue.
''' </summary>
''' <param name="maxValue">The maximum value. Must be greater than zero.</param>
Public Function [Next](ByVal maxValue As Integer) As Integer
     Return [Next](0, maxValue)
End Function

''' <summary>
''' Generates a random integer between minValue and maxValue.
''' </summary>
''' <param name="maxValue">The lower bound.</param>
''' <param name="minValue">The upper bound.</param>
Public Function [Next](ByVal minValue As Integer, ByVal maxValue As Integer) As Integer
     Return CInt(Math.Floor((maxValue - minValue + 1) * NextDouble() + minValue))
End Function

''' <summary>
''' Generates a random floating point number between 0 and 1.
''' </summary>
Public Function NextDouble() As Double
     Return NextUInt32() * (1.0 / 4294967295.0)
End Function

End Class