Quite possibly the most unique bullet heaven game out there.

Shadowkin's distinctive aspects are readily apparent. The first is the presence of your ally character, a mechanic I've not yet seen executed in the genre. The advantage of this is obvious: double the characters means double the upgrades, which, in a genre that's pretty much defined by its copious upgrades, is a huge boon. The other cool thing about bifurcating players' builds is that you can optimize which upgrades go on which character; considering that elemental interactions are an important part of the game, figuring out how to best craft each of your two characters to optimize these systems is an interesting twist to the normal formula.

The other, more significant thing that Shadowkin has going for it is that you go on ACTUAL RUNS. Most bullet heavens plop you down in big, open field that never really changes over the course of a run. Shadowkin, instead, has you advancing through multiple different rooms and zones like 'typical' roguelites. This is a massive boon for the game, as it keeps runs much fresher: not only do the changing backgrounds keep things interesting from a visual perspective, but they also keep the gameplay fresh, as room layouts will change how you approach hordes, and zone-specific elite enemies have unique attacks to avoid. This multi-zone run structure alone makes Shadowkin stand above a huge swath of the genre.

The game does have its drawbacks, though. A recurring a complaint I see is visibility: I agree, but I do think the complaints are overblown. Yes, the screen does get hectic from both player and enemy attacks, which will occasionally lead to instances of "unfair" damage. However, the "difficulty" of the bullet heaven genre lies in crafting a build that can out-DPS enemy health scaling, and Shadowkin is no exception. If you're losing a run, it's not because of unavoidable attacks; it's probably because you didn't build well enough. And, that being said, if you hyper-focus and really sweat your dashes, you can dodge somewhat effectively amongst the chaos.

The other, bigger flaw of Shadowkin is that... there's just not enough content. You will see most of available attacks and ESPECIALLY most available relics in just a few runs. In terms of attacks, builds are defined more by which attacks you've maxed (which takes significant investment during a run), so attack variety is less of an issue. The relics, however, will become VERY familiar VERY quickly. I actually think the relics are pretty awesome in terms of design, but there are just too few of them. There are about 25 in the game total, and you'll be able to get about 8 each run. That's a third of the total relics each run on its face, but, since you're always offered a choice of three, and relics are divided into tiers that you can actively seek access to as a room reward, you will basically see every relic every run. But it goes further than that - not only will you SEE most of the relics each run, you'll probably actually GET the ones you want each run. Considering that relics are the big "synergy setpieces" of your build, getting the same ones over and over again tends to homogenize how builds feel. This could be solved by the developer adding more relics; however they've stated on Discord that there will be no further development on Shadowkin due to poor sales, which is unfortunate for both the developer and the players.

Now, despite these flaws, I do think Shadowkin is ultimately a fun game. It may not have as much content as some of its genre peers, but I think the quality of design for what IS in the game is very good. A lot of bullet heavens feel like "minimum viable concept" games, with the absolute barest of gameplay mechanics to make them function - that's usually movement as the ONLY input in a play space that comprises a single screen. Shadowkin feels a lot closer to a "normal" roguelite with deeper, more mature run structures on top of all the wacky, OP character upgrades you'd expect from the genre.

If it's not clear, I think Shadowkin is very much worth playing. I'm actually not normally a huge fan of bullet heaven games, as they tend to be a bit too simplistic for my tastes, but Shadowkin really sucked me in more than I expected it to. If you like bullet heavens, you'll definitely like Shadowkin. And, even if you're only marginally interested in bullet heaven games, you may still enjoy Shadowkin, as I do. Seven bucks is a really modest price for what's on offer (beyond gameplay, the visuals and especially music are pretty great), so I'd say go ahead and up the game if you're interested! I think it deserves more attention than it's gotten.