You had to figure this wouldn't last. Though some publishers have been willing to strike agreements that allow fan projects to go forward, provided no one sells anything from them, many more don't have the time or the interest in maintaining and monitoring those relationships.
So when it came to light last year that some Brony devs were putting together something called My Little Pony Online, it seemed destined to end with a C&D from Hasbro, makers of the toy line/ironic lifestyle brand at some point. Still, they pressed ahead, releasing the game's first episode about a month ago. Shortly thereafter, the MLPOnline team got a shutdown demand from Hasbro's lawyer-mans.
A statement from the team was very careful not to blame Hasbro for the shutdown, even though the game was being scrapped essentially because of a legal threat involving copyright and trademark infringement.
"Hasbro is not to be blamed here, they wrote. "As per US Trademark law, as soon as an infringement comes to light, they are obligated to defend the trademark, or they will lose it. They had no choice in the matter, regardless of what they thought of the project or how it benefited them."
The statement added that "there was little we could do to work around it. ... Discussions continued through the month, but it came down to one fact: MLP:Online had come to an end."
All is not lost, Bronies. About three-quarters of the original team remains intact, changing its name to Starlight Studios. "We have selected a new project. It is pony related, but otherwise we're keeping most of the details secret," they write. "It is our goal to have it completed by Bronycon 2013, though this may be ambitious."