An excellent game. Some stuff holding it back being a few underdeveloped areas, a mediocre ending and an overall poor implementation of the Metroidvania formula.
To elaborate on the last part, there are very few optional ugrades to be found, sidequests do not reward you with interesting things, the soulslike currency and levelling system is weakened by the Level ups and items to buy being underwhelming.
The difficulty is great imo. Without any grinding whatsovever I ended on 1 of 3 stats upgraded to the maximum, the other just behind, and had little trouble with most bosses or fights, taking a death or two here and there, but nothing difficult or easy enought o make me frustrated or bored. The realtive cheapness of combat potions which would have likely made most fights trivial provide a good way for less skilled players to get throught difficult fights. That's how beat the secret boss as well, which in my opinion is A: Too difficult compared to erverything else in the Game. B: Not funat all and C: Remarkably disappointing in it's reward. What do you mean the secret challenge boss has a single H-animation without any unique Game-Over?
It's all a bit surface-level, unfortunately. The dev has a good undestanding of both soulslkike/Lovecraftian worldbuilding and visualdesign, as well as a good sense of balance and gameplay design. But aside from a few theoretically convenient but more than likely never used items and a flotation ability with feels like it was implemented with a lot more in mind that what was put into the game, thereis just not that much to discover, a fatal flaw for any Metroidvania.
There has been a lot said about the Ending being disappointing, and unfortnately I have to agree. A second phase to the final fight would have done wonders for me, but admittedly I wasn't that interested in the story. I have to admit, i did not get what the credit scene implied, possibly because I just instinctively attacked the enemy, and what probably could have been a decent moment fizzled out into genuine disappointment.
Despite some Flaws, Sinistar2 surpasses it's predecessor, which was also great but dipped heavily into frustration with various designs. I hope it will continue to get developed, and if you have the ability to buy it, I recommend you do.