Now, this is fairly recent release, but the fact that a Space Harrier-alike with actual sprite scaling and stuff managed to exist for almost half a year before I'd even heard any mention of it qualifies it as obscure, in my mind. I'm glad I did eventually hear about it, too, as it turned out to be pretty good!
I'd even go as far as to say that it feels like it could be an actual Space Harrier sequel! It doesn't really add a lot to the formula, mostly being, like its forebear, a basic sprite scaling shooting game, with no lock-on attacks or other things added by later games like Afterburner and Galaxy Force, but the couple of elements it does add are ones that really fit, and definitely add something to the game, in the way that a sequel would. (I know there actually was a Space Harrier II, but it was one of those early Mega Drive "straight to video" sequels like Golden Axe II that only really offered more of the same. Not that there's anything wrong with that, though!)
There's two main mechanical additions to be found here. The first is a meter at the bottom of the screen, filled by collecting coins. Once it's full, another character will fly in and join you, acting like an option in a more traditional 2D shooting game. The second is a melee attack that you can use to hit enemies that fly in close to you, and more importantly, to cancel enemy bullets. These are both great additions, though it might have been interesting to build on them both a little more. Say, incentivising use of the melee weapon by having it score more points than defeating enemies with shots, or by having cancelled bullets turn into coins that fill the meter, maybe?
Something I haven't mentioned is the connection to the Hyperdimension Neptunia series, which is mainly because I haven't played any of them and I have no interest in changing that. It doesn't really affect anything about how the game plays, though, andaesthetically, it looks amazing too, so any effect it's had there is obviously a positive. The sprites are all big and colourful, the stages look great, and it does some cool stuff with sprite scaling, too. The bosses in particular: a dragon swipes at you with his massive claws, and a big frog monster tries to grab you with his stretchy multi=sprite tongue.
The only real negative thing I have to say about the game is that it is a bit short and a bit easy. They should definitely at least have labelled the "normal" and "hard" difficulties as "easy" and "normal", respectively. Still, it's only a couple of pounds, and even if it only takes a single attempt to 1CC normal mode, and not many more to get through hard, it's enjoyable enough that it's definitely worth it. Finally, a few people have asked me to mention where I get the PC games I post about, so starting with this one, I'll do that. This game is available on steam, and the past few PC games I've reviewed were bought from DLsite.