So, Logiart Grimiore being early access, they haven't implemented keyboard or gamepad support. Steam deck handles that nice with the touchpad and triggers mapped to the mouse. I've done 4 puzzles, and yep, it's Jupiter Picross, with the same music cues when you finish up a puzzle. The beginning tells you that only mouse is working, but it gives you the option for buttons when starting a puzzle. The dpad worked, and maybe one button worked to select a square, but I couldn’t mark an unused square.
They referenced a Fusion system which didn't do anything other than add in a step to unlock some puzzles. Maybe that does something more later on? I dunno. There’s a little Vivi/Orko wizard who tells you all the stuff, and I did the first tutorial just because, which was quite good. Had a little animation showing you how to chart out overlapping squares.
I’ll try more sometime. The description said they get into some large puzzles, up to 40x30, and I like those when Jupiter’s consistent rules are applied. Maybe the extra stuff will be interesting?!? If not, it’s still good Jupiter design.