"Random" Number Generator

[TechSY730]

In the 4.067 release notes:

Fixed a surprisingly longstanding (but heretofore unrecognized) bug that was making the random number generator sometimes be highly non-random. This was leading to things like a very odd default pattern of collision offsetting.

Obligatory XKCD link anyone?

[keith.lamothe]

Interestingly, 4 is the exact number of distinct results random.Next(0,360) was producing when picking a random angle (in degrees) for collision offsetting.  Not on every starting seed, but on a fair number of them, it seemed.

[x4000]

Even more interestingly, "surprisingly longstanding" means "as long as Mersenne Twister has been used in the game" or "since prior to 1.0, sometime before license keys existed for the game."  That's crazy long, and I'm shocked this hasn't been more of an issue before.

[x4000]

Going back and looking at the logs, I now see why this was never a problem: I got rid of the float conversion the very day I implemented Mersenne Twister here, which was March 6, 2009.  Well before I even thought of adding license keys.