Endless Shirafu has launched their latest mainline STG on Steam: ∀stralbringer -Shaded Arkarium-, a very loose successor to 2012's ∀kashicverse -Malicious Wake- and another game squarely in the post-Hellsinker mould, both aesthetically but also in terms of experimenting with progressive ideas—the game's designed around mouse control, for one, and there's a heavy emphasis on the shop system, etc. I'd say it's a good bridge between a more traditional danmaku game and some of the more out-there doujin stuff; "Psyvariar ADD" is one descriptor I saw recently, and I suppose that tracks.
(The game's content-complete save for the English localisation and whatever bugfixes are required; the full launch with English is planned for February/March.)