Kernel Hearts Review

A Magical Girl Roguelike with a Very Strange World

Kernel Hearts is the debut game from Argentina-based indie studio Ephemera Games, published by Whitethorn Games. It released on September 17, 2026, and combines several ideas that don't normally appear together: magical girls, biblical imagery, science fiction, a post-apocalyptic world, hack-and-slash combat, and roguelike progression.

The basic idea is already enough to make the game stand out. You play as one of four magical girl soldiers from the M.A.H.O.U. Unit, climbing the Tower of Babel while fighting angelic creatures. Humanity is close to destruction, and your ultimate goal is to reach the top of the tower and defeat God.

Kernel Hearts is not a sequel or part of an established series, so Ephemera Games had plenty of freedom to build its own world. That shows in the game's unusual combination of anime-inspired characters and a dark post-apocalyptic setting. It is a strange concept at first, but the more you play, the more the different pieces start to fit together.

The story begins with humanity making contact with something far beyond its understanding.

The game eventually introduces magical girls with supernatural abilities, which humanity turns into weapons. Those events lead toward the creation of the M.A.H.O.U. Unit and the world that exists when the game begins.

The world is drowning in ashes, while the massive Tower of Babel has appeared and become the center of the remaining conflict. The M.A.H.O.U. Unit is sent upward to fight the creatures inside the tower and eventually confront God.

The game's story is one of its more interesting parts because it does not simply use a typical fantasy setting. Biblical ideas are mixed with anime character designs, science-fiction concepts, and a post-apocalyptic world. Angels are enemies, magical girls are soldiers, and the Tower of Babel becomes the main place where everything comes together.

You can also interact with characters between expeditions. You can spend time with them and build relationships, giving the game a little more to do outside of combat. These interactions are not always as developed as the main action, but they help give the characters more personality.

The story can sometimes feel more interested in its atmosphere and unusual ideas than explaining everything clearly. Even so, the setup is interesting enough to make you want to see what is waiting higher up the tower. Kernel Hearts is built around repeated expeditions into the Tower of Babel. You enter an area, explore it, fight enemies, collect resources, become stronger during the run and eventually face a boss.

The areas are more open than you might expect from a roguelike.

Instead of moving through a series of small rooms, you can explore larger spaces, find enemies, search for resources, and discover areas off the main path. The demo's opening area, for example, gives you a large field to explore with ruined buildings, hidden areas, and petrified angels that can come alive when attacked.

This makes exploration an important part of the gameplay. You can rush toward the next objective, but taking some time to look around can give you more resources and opportunities to improve your character.

The game can also be played online with up to four players, so you can complete expeditions with friends. This works well with the game's overall design because larger battles become much more chaotic when several players are attacking at once.

Between runs, you return to the game's hub and use the rewards you collected to improve your character. One of the main customization systems involves chips you can equip to your MAHOU.OS unit. These provide different bonuses and let you tailor your character to how you prefer to play.

The game also features a magical-girl transformation system. During combat, you can build up enough power to transform into your character's true form and unleash a stronger attack. It fits the game's theme well without feeling like it was added purely for appearance.

Overall, the gameplay loop is simple: enter the tower, explore, fight, collect resources, get stronger, reach the boss, and return to improve your character before trying again. Combat is where Kernel Hearts is at its most action-focused. You fight enemies with normal attacks, abilities, movement, and dodging, and each character has their own style.

The combat is easy to understand and doesn't require you to learn a huge number of complicated systems.

You can move around enemies, avoid attacks and use your abilities when you have an opening. The magical-girl transformations also give combat a useful burst of power when you need it. Bosses are generally the strongest part of the combat. They have more noticeable attack patterns and require you to pay attention instead of simply attacking constantly.

Some reviews have specifically praised the bosses and their ability to make you pay attention to what is happening around you. Regular enemies are more mixed. Once you understand your character, some encounters can feel repetitive because you often use the same attacks against similar enemies. Some players also complain about hit feedback and the clarity of attacks during busy fights.

That is probably the biggest weakness of the combat. The game looks like it should have deep, satisfying hack-and-slash combat, but it doesn't always reach that level. The basic fighting is functional and can be enjoyable, especially against bosses, but it lacks the depth of some of the games that clearly influenced it.

Still, the combat becomes more enjoyable as you experiment with different abilities and builds. Playing with others also helps, because fights become more active and less repetitive when several characters work together.

Progression in Kernel Hearts is split between what you gain during a run and what you keep afterward.

During an expedition, you can collect Stray Souls and use them at Moon Shrines to level up. This means exploration directly affects how strong you are when you eventually reach a boss. If you rush through an area without collecting anything, you may reach the end without gaining as much strength as you could have.

The other side of progression happens after a run. You can use resources and rewards to improve your character and customize your MAHOU.OS unit with chips. This system works well with the roguelike structure because dying does not completely remove your progress. You can return to the hub, make changes and try another run with a better setup.

The downside is that the early permanent progression can feel slow. Some reviews have pointed out that early upgrades are limited and that resources do not always immediately benefit the build you are currently using. Once more options become available, however, the progression becomes more interesting. You can start experimenting with different setups instead of making the same upgrades every time.

Kernel Hearts has a very recognizable visual style. 

The magical-girl characters stand out immediately, while the world around them is much darker and more damaged. The contrast works surprisingly well. You can have a brightly designed anime character fighting an enormous angel in an area covered in ash and ruins, and it still feels like it belongs in the same game.

The environments also give you enough space to appreciate the setting. Ruined buildings, large fields and strange structures make the Tower of Babel feel like more than a collection of combat arenas.

The character portraits are particularly strong, and the main characters generally receive more visual attention than the regular enemies. Reviews have praised the environments and portraits while also pointing out that some enemy models and animations are noticeably less polished.

A lot can also happen on screen during combat. Effects and attacks can sometimes make it hard to see exactly what is happening, which ties into some of the combat feedback issues.

Even with those problems, the art direction is one of the game's strongest qualities. Kernel Hearts has a look that is easy to recognize, and the combination of magical girls, angels and a ruined world gives it plenty of personality.

The soundtrack is one of Kernel Hearts' more consistent highlights.

The music shifts styles by area, helping each part of the tower feel distinct. Rather than relying on one sound throughout the game, the soundtrack moves between different moods and genres. The combat sounds also help make the bigger attacks feel more important. 

There is a lot happening during battles, and the music does a good job of keeping the action moving. The game's audio is arguably stronger than some parts of its combat presentation. Even when the visual effects become hard to follow, the music keeps the game's atmosphere strong.

Kernel Hearts is an unusual game, but that is also what makes it interesting. It takes magical girls, angels, biblical imagery, science fiction and roguelike action and puts them into one game without trying to hide how strange the combination is. The result is not perfect, but it has a clear identity. The story and setting are probably the biggest reasons to keep playing.

The world is different from the usual fantasy or science-fiction setting, and the Tower of Babel gives the game a strong central location. The characters also have enough personality to make the non-combat sections worthwhile. The combat is more inconsistent. Boss fights can be enjoyable, and the character abilities and transformations fit the game's style well. Regular encounters, however, can feel repetitive, and some players may find the hit feedback and animations less satisfying than expected.

The progression system works well enough for the roguelike format.

Leveling during runs gives you a reason to explore, while permanent upgrades give you something to work toward after a failed expedition. Early progression could be faster, but later customization is deep enough to make different builds worth experimenting with. The visuals and soundtrack are probably the game's most consistent elements. The anime-inspired characters look good against the ruined world, while the music gives each area its own identity.

Kernel Hearts is also a debut, and that is worth keeping in mind when you look at its rougher parts. Ephemera Games clearly has a strong visual and creative direction, even if some gameplay systems don't feel as polished as the presentation around them. There is a solid foundation here, and the game's strengths suggest that future updates could build on it.

At its best, Kernel Hearts is a stylish action roguelike with an unusual setting, fun bosses, and a soundtrack that makes the climb up the tower feel worthwhile. At its weakest, the combat can get repetitive, and the progression can feel slower than it should. It has a lot of personality, and that goes a long way for a first release. There are some rough edges, but they don't completely take away from what the game does well. If the developers continue building on its ideas and smooth out some of those weaker areas, there is plenty of room for Kernel Hearts to become an even stronger experience.