I don't know what exactly made me try this game, as I've long thought that IGS' beat em ups are mostly very similar: expanding wildly upon the concepts of inventories and levelling up put forth in Capcom's Dungeons and Dragons and King of Dragons games. The main thing that interested me in Knights of Valour 3 was the fact that it used memory cards to save progress in a way that's more common in rhythm or racing arcade games. Still, whatever instinct drew me to Seven Spirits turned out to be a good one.
First, I want to talk about the presentation: it uses a combination of 2D sprites on 3D backgrounds, which is something you see more in home games than arcades (the only other arcade examples I can think of off the top of my head are Strider 2 and Dolphin Blue). It's a style that almost always looks great, though, and this is no exception. The characters are all well-drawn and well-animated, and the bosses playable characters all have really cool designs, too. There's something about the character designs and the colour palettes that really feels reminiscent of Chinese martial arts comics, which is something else in this game's favour, since that's an aesthetic well that's not drawn from enough by videogames in my opinion.
The game's structure is also worthy of praise. Each character has their own starting stage, and after that, you're usually given a choice of which stage you want to enter next. And it's not a case of choosing the order in which you want to tackle the stages, but rather there are three possible stage twos, three possible stage threes, and so on. So it adds up to this game having a ton of stages, and it's only possible to see them all over the course of several playthroughs.
As for how it plays, it doesn't have the RPG-inspired stylings of its stablemates (which might be why it's got a subtitle instead of a sequel number? I dunno), being more of a straightforward beat em up. You've got three buttons: weak and strong combo attacks, and jump. Pressing two adjacent buttons at once activates one of your two super attacks, which are limited by your stock of pearls. You've also got a meter that gradually fills up as you take damage, and once it's full, you can press weak attack and jump together to go into a powered-up mode that lets you use as many supers as you like for a short time.
I've really enjoyed the few hours I've spent playing this game, and I look forward to a fair few more of them, as I want to see all the different locales it has, and fight more of the cool bosses. It really is a shame it's never had a release on a home console, especially since it could easily have been hosted on the Dreamcast, a system with a massive hole in its library where beat em ups should have been. Still, you can play it now via emulation, and I recommend that you do so.