And the icing on the cake is the "btw, we are giving you the exclusive so keep it secret".
Like, wtf. He ain't TechCrunch. Why the fuck are they giving him that exclusive? Nothing yells "we stole your stuff, but dude it was open source so you really can't complain, and thanks for the idea" more than that.
You can't make up this shit.
Last year a huge game company released something built on my tiny open-source game engine (uncredited), and I only found out about it later from a kind internet stranger. All things considered, better to know in advance so you can at least have your own response ready, so you can comment in the relevant HN/reddit threads, etc.
That said, the "keep it secret" part of the mail here does sound weird, but given the other history there may have been an NDA in place.
That said, in my case the summary makes it sound better than it actually was. The game they released was a one-off promo thing, which made a big splash for a few days but was effectively dead by the time I heard about it a week or two later. Then there followed a dialog with a separate team inside Microsoft, about hopefully updating it, which dragged on for a while and basically resulted in their bit getting updated but not mine, etc. etc. Altogether it was a big distraction and a pretty dreary episode.
Not clear if they were trolling or just tone deaf.
As opposed to the other tech bloggers who will have a scramble to write it after hearing about it with the rest of the world