I finally figured out what's been bugging me about Treasure.

[DEL]

In my opinion, its got nothing to do with RSG or Ikaruga being Vert or Hori. Its got everything to do with them being puzzle games. Not really shoot'em ups. But that's just my taste.
I remember Plasmo giving me a masterclass in RSG play at the Milan Meet in 2006, so I do have some appreciation for it. But, just not my thing.

[Friendly]

Its got everything to do with them being puzzle games. Not really shoot'em ups. But that's just my taste.

Not just yours.

[Special World]

tbh I don't really get why people like to call Ikaruga a puzzle game, but they don't say the same thing about the Dodonpachi series. Neither game really feels at all like a puzzler to me, but imo puzzling out DOJ is just as involved as puzzling out Ikaruga. Puzzle games are all about manipulating the blocks, and there's really nothing you can do to manipulate enemy placement in Ikaruga. I feel like people just like to latch onto the fact that Ikaruga is different from other shooters, and take that to mean it's not a shooter, sort of like how Smash Bros is a "party game" instead of a fighter. Both games are way, way more like their stated genre than the other genres people like to lump them into. Ikaruga shares much more common heritage with shooters than it does puzzle games. I would never, ever, ever get a craving for a puzzle game and end up popping in Ikaruga.

[Squire Grooktook]

Yeah, so far I don't see Radiant as a puzzle game so far. Chaining seems to take memorization, but it's got nothing on something like R-Type in terms of figuring out how to manipulate the enemies to survive.