Name a few, besides Deadly Premonition I can't think of any really obscure game (not counting underrated, on GAF everything is either over or underrated) this gen that came out in the West.
Guess game development just has become so freaking expensive most companies just aren't willing to take the risk anymore..BUT: as developing for HD platforms should get cheaper (I assume) we might see a resurrection of games that make you scratch your head how anyone in their right mind gave the greenlight (aka the best games)
Yeah, Deadly Premonition is definitely a lost Dreamcast/PS2 era game. I hear what you're saying though. There aren't as many HD "niche" games as I'd like there to be. I mean, you've got your oddball Japanese alternative RPGs/games like Nier, Folklore, Majin, & 3D Dot Game Heroes, but these kinds of games just aren't as numerous as they used to be. There's just so little on the system and I don't see there being much more of a library in the coming years. There's nothing really to discover, you know what I mean? Basically, if you are a hardcore gamer and you like to try and keep on top of everything, it's really not that difficult to have played (or at least be aware about) all the "niche" alternative/obscure games on the system.
As I said in my last post, I think what you're looking for can be found (somewhat) on the DS and PSP primarily and soon to be 3DS and Vita. Other than that I think the Wii is where all of the weirdo games have been housed this "gen" other than what has been released on the portables. Just look at this assortment of 12 games:
This is an extension of the PS2. Take games like Tenchu: Shadow Assassins and Sky Crawlers, for example, and compare them to their HD counterparts. Which games are more true to their lineage? Shadow Assassins or Tenchu Z? Assault Horzion or Sky Crawlers? Christ, forget even what feels more like a PS2 game. The Wii games are just better games in general than their HD brothers! I just feel like devs experimented more on the Wii (which in retrospect makes sense since the platform/controller was so different) than any other console this gen.
Anyway, I genuinely feel like the Nintendo Wii provided that PS2-like library. While it may not be there in quantity, there's far more obscure/underground/underplayed games on the Wii than there will ever be on the PS3.