Hmmm.. I've now beaten everything in the pre-2.103 build but I can't seem to figure out Rounders.. Do I have to find a way to keep the blackhole in the south-west clear?
possible bug and spoilers below the fold:
I could be mis-reading the level intent (given that I haven't remotely figured it out!) but if you literally do nothing, the lone square-block seems to end up where you probably want it to be:
I'm assuming that you're supposed to trigger that by doing something like this (and sometimes when you do this, it can result in the pusher getting stuck in the little alcove to the right):