most of us publish on scirra arcade to get feedback of our unfinished works, for polished work, we go the traditional way of doing advertising, however Scirra arcade its a good place to start as any other no matter of the stage of your projects ie. Alpha,beta etc...
one reason most of polished games in scirra arcade are because of the bellow statements.
Posting Stats on scirra community forum to date (take or give 10k on total posts/topics cause of the bots that where flooding lately this year )
595,217 total posts 200-500 posts daily .
117,685 total topics 50-150 topics opened daily.
273,118 registered users --- 5-10% active all time in forum
as you can see the community it has a bit of a kick in it... and can help you push your first project marketing to a next stage from beginning.