How is this game using just a controller?

[Joerpg84]

It says full controller support and wondering if it’s fully playable on an ROG Ally or Steam Deck as a bullet hell.

[Jezze]

I answered a similar question some years ago:
https://steamcommunity.com/app/940680/discussions/0/4197887985797172397/

In boss fights you walk normally with the left stick and "enter" letters by press the L or R bumper, depending on the visual hint above the text (for the next word) or above your head (for the next letter).

Unfortunately, there are some minor issues with the controller outside of the boss fights that were never addressed.

[Thoth Shoggoth]

Sounds like a different game to me