As may have been previously established, I'm a shmuck for cool Famicom stuff. So I went and acquired the Spicy Ver. as well.
I like how the covert art is the same scene but from different perspectives, other than that Normal Ver. takes place during the day, and Spicy Ver. it's during dusk. But this also matches the in-game palette, so it's still cool.
The differences between Normal and Spicy were already listed above. It's a bit more difficult, the hidden score bonus items are re-located, and the enemies behave differently, so you gotta re-learn the whole thing, basically. The scenery you fly over is still the same, at least, other than the color palette.
I haven't been able to unlock any hidden game modes yet. I've seen mentions of both 1-Minute Mode and Super Spicy Mode, so maybe there are two hidden modes? I tried scouring through the dev's Twitter posts and what YouTube videos I could find for any hints, but to no avail.
The devs are really trying to re-create the Famicom era zeitgeist. In addition to Normal Ver. and Spicy Ver., they also released HabiT! Spicy Dosanko Ver. which was sold exclusively in an event held in Hokkaido. As far as I could surmise, it's the same as Spicy Ver, but with a white cartridge, the enemy sprites are different yet again, and the ground's color palette is changed so it looks like it's covered in snow, appropriately for Hokkaido. But that's even more interesting is that they're hosting tournaments this summer, Hudson All-Japan Caravan Festival-style, for both Normal and Spicy Versions, with the winners getting a Golden Cartridge as a prize!
https://www.gameimpact.info/habitstg2024/
That's pretty awesome, and as someone who's always liked caravan modes it breaks my heart a little bit that I can't take part. BUT here you can also participate by posting a video recording of your run and sharing the link in Twitter with the hashtag applied, as is the way of times. I'm pretty sure that's not applicable for the Golden Cartridge competition, though. I'll still try to post some entries for the fun of it.