I've noticed the lack of reviews that were backed by fair amount of playtime, I'll scribble my own things down now that I've completed the game entirely
In the shortest form NSI is a niche rogueli-k-t-e deckbuilder that requires field management aside from the deck, this alone is what makes it feel different than other roguelike deckbuilders
Generally gameplay representation looks a lot different from any other by design choice, for example you conquer some map regions in this to progress, and every X fights intervals you face a core boss, but technically it's actually pretty same with any other deckbuilder mapping system, just visually served differently, I think it was a nice change of pace.
You begin your runs as a big bad dragon with massive health pool and absurd damaging cards, you have limited healing sources throughout your run and your goal is to refine your deck and maybe get some relics before facing the last boss to conclude the run, this part is pretty familiar, right?
Then comes the field management system. It's not mandatory to play into this, but I can easily say this is the intended way to play the game. There are some elements, each dragon (there are multiple!) has some extra unique element too, and whenever you cast your abilities on any portions of your battle field, you leave traces of these elements, and when multiple elements are merged magic happens, be it shielding, area damage, poison, burn, you get it. Playing in this fashion, it requires more of the active 'thinking' as you are required to keep up your management during the fights (this may feel overwhelming to some) and more often than not it'll be you instead of rng that decides the fate of your encounters.
Now the cons:
Can get buggy at times, it's not horrible, but can be annoying time to time
There are several 'cheese' builds you can follow, these will likely trivialize the need of field management part of the game
Meta-progression is a necessity to use in order to succeed in higher difficulties
Overall it's a nice and different game, if you are one of roguelike deckbuilder addicts, you should give it a go, but be warned, field management requires active thinking so it might not click with everyone
