Summary:
1980-2000: D&D was owned by a succession of companies named TSR and was involved in a lot of lawsuits about who could publish material to be used with D&D.
Early 2000s: Wizards of the Coast (WotC) has bought D&D and wants a less hostile relationship with the rest of the industry. Also wants other companies to make things like adventures that work with their game (because they're relatively high cost and low volume, compared to the core books that WotC sells.
They license out the core game mechanics under an open license and lots of games are published using compatible rules.
2008-ish: Hasbro has bought WotC and releases a new D&D edition (4th Ed). They do not offer the same sort of license terms and the product is not as successful.
One of the big 3rd party publishers (Paizo) forks D&D into Pathfinder and has ok success.
2014-ish: Hasbro/WotC releases D&D 5th edition. Ultimately releases the core mechanics under the same licensing used for 3rd and 3.5 edition in the early 2000s.
A month ago: Hasbro-WotC announce they want to retroactively revoke the license from the early 2000s and collect royalties from companies like Paizo.
They are also in a legal tiff (in which they're on the side of decency) with a new company named TSR, operated in part by the son of Gary Gygax, which specializes in making offensive and incredibly racist, sexist, etc... material.
Only thing missing from that roll up is that the WotC Vp for the 1.0 license came out this week and said when they created the license, they specifically left.out any revocation method, because of future asshats doing shit like this. There is some very legal questions if WotC Hasbro can do anything under the old license because it's specifically in perpetuity without a revocation method.
(Doesn't stop new thing from going under 2.0 though:/ )
I'll be back for an edit with the source interview when I did it out oy my history.
Not the one I was looking for but relevant anyways:
"Unlike a bare license without consideration, an offer to contract like this cannot be revoked unilaterally once it has been accepted, under the law of Washington (where they are located) and other states."
That's from EFF analysis posted by another here in this thread.
