There’s something so pure about the boss rush genre that I can’t help but be drawn to it, and when I saw that the debut release from Brazilian developer Lobo Sagaz Studio combined the aesthetic of Silksong with some impressively unique boss rush gameplay, I was definitely curious to give it a shot. Through its dominant black and white color scheme, one-on-one combat, and sword-wielding protagonist, it evokes Japanese samurai films. It also employs a novel progression system in its run-based structure that rewards experimentation and learning from your mistakes. More than just your powers of observation, Gurei also requires a deft hand and precise timing to make your way through its punishingly tough gauntlet of opponents.

You play as heroine Rei, who awakens under a sigil of colorful flames within a ruined castle. From the centre of the castle, you're given the freedom to choose your path, seeking out the 10 bosses whose likelinesses are made physical in a statue just above your starting location, a statue that's very much akin to the same in Super Metroid. Your first real task is to locate each of your opponents, none of which is too far away. Each presents a unique fight and bestows a special ability or power when you conquer them, but they also scale in difficulty the more bosses you eliminate.

And therein is Gurei's greatest trick: the more powerful and capable you become, the more adept your foes become. How this manifests is both in terms of Rei being unable to do as much damage with her basic strikes given more stout defense that she faces, but each boss also has more tricks up their proverbial sleeves. If you choose to take on the red Snake first, you’ll find that it has really only two attacks; if you wait until after you’ve taken down half a dozen other bosses first, the bout becomes much more challenging, with four or five different attacks you need to watch out for. Some of the ways that the boss fights change depending on when you initiate them are really interesting, like the yellow Peafowl at first giving you a choice of which weapon it brings into battle and later forcing you to engage it with all of its armament equipped. The more you play, the better sense you have of which boss orders are more favorable and which are an absolute nightmare. The encounter with the orange Catfish is child’s play at level 1, but leave it for one of your final four and its robust exterior and increased arsenal may be too much to overcome.

Another wrinkle that needs to be underscored is that Gurei is run-based and doesn’t let you carry over progress from one run to the next, outside of minor interactions with spirits and other denizens haunting the castle. Every successful boss encounter gives you an extra life to use in future fights, but once those run out, your run is over and you need to start over from scratch. The ominous “last chance” message that displays prior to starting your last life is a glaring reminder that it’s truly do or die, and so maybe you choose to take on a different opponent with the hope that the skill they pass on to you could be the one to push you a bit further along. Defeated bosses also make a running commentary during the rest of your run, potentially offering advice or sharing their feelings about an upcoming encounter. My prevailing sentiment was that I really enjoyed experimenting with different boss paths and learning about which skills worked best with my playstyle, but the built-in delay with Rei’s dodge did leave me feeling frustrated fairly often.

Gurei takes a growing modern genre and adds some novel wrinkles to it, creating an ultimately unique experience. One annoying issue with the game is the high number of crashes, which forced me back to the Switch home menu on nearly every run; the game’s autosave meant I never lost any progress, but I was constantly worrying that I would experience a crash during one of the boss fights, rather than before or after–which added unnecessary tension beyond what the game was already offering. I’m a major fan of how the bosses scale up as you take down their compatriots, leading to tough but meaningful choices as you plan out the route of each run. Those who enjoy the difficulty of titles like Hollow Knight, Blasphemous, and Nine Sols will relish how much Gurei pushes you, but it will need a patch to address the crashes before I wholeheartedly recommend it.