These days I'm inclined to leave a word with its existing common/rare status unless I'm sure a change is warranted. I'm not sure about
emptily. Writers use it in various senses and it doesn't necessarily seem awkward. A couple of examples from books in the British National Corpus: firstly, a literal usage, from
King Cameron, by David Craig:
Aberfeldy was a ghost town. The laddering and scaffolding round the half-built mill reared up emptily like the skeleton of a forest.
And a figurative sense, from
The Best Man to Die, by Ruth Rendell:
Yawning ponderously, he put Clytemnestra outside the back door and while he waited for her, stood staring emptily at the cloudless, star-filled sky.
I don't think many players would doubt that there is such a word as
emptily. They might not think of it, but that's what the fiendish game is all about.
I'm going to leave it as common.