Sipho

Some games sell you a fantasy. Sipho sells you a laboratory. Developed and published by the small studio All Parts Connected, Sipho launched on Steam on September 30, 2023, and drops you into the murky deep with a single, easy-to-grasp mandate: build a monster, then eat everything smaller than it.

This is an action-survival game that borrows its spine from an unlikely lineage. Take the cell-devouring escalation of agar.io, splice in the modular-construction obsession of games like Reassembly or Nimbatus, and stew the whole thing in the genuinely unsettling biology of siphonophores—those real-world colonial sea organisms that look like a single animal but are actually a democracy of specialized parts. That last detail isn’t set dressing. It’s the entire design thesis.

You don’t play a creature in Sipho. You play a colony. Your organism is assembled from zooids—modular parts, each doing exactly one job. One eats. One swims. One fires a spike. One just sits there and holds the structure together like biological rebar. Bolt them together and you get a living, wriggling machine of your own design, then send it careening through procedurally generated waters to climb the food chain.

The market positioning is honest indie: this is a niche builder-survival hybrid, not a blockbuster, and its audience reflects that—a devoted cult rather than a mainstream hit. That framing matters. Sipho is a specialist’s game about a specialist’s fantasy: the pure, tinkering pleasure of watching a system you designed do something you didn’t fully predict. It nails that fantasy. It struggles with almost everything you’re supposed to do around it.

• Modular Zooid Construction: The core hook. Assemble creatures from functional parts—eaters, movers, attackers, projectile launchers, structural supports—each with a distinct role. The combinatorial space is the whole point, and it’s deep.
• Campaign Mode: Battle through procedurally generated, effectively infinite worlds teeming with hostile life. Each run doles out different zooids to unlock, nudging you toward playstyles you wouldn’t have chosen.
• Aquarium Sandbox: A freeform mode with unlimited tools and no survival pressure. Design creatures, stage scenarios, and experiment without a clock or a predator breathing down your membrane. For many players, this is the real game.

The Gameplay Loop

The moment-to-moment of Sipho is a tug-of-war between two very different games, and only one of them is fully realized.

The first game is construction, and it’s excellent. You start small—a sad little cluster of parts—and every meal is currency. Devour enough nutritious food and you earn the resources to graft on new zooids, reshaping your creature mid-run. This is where Sipho sings. There’s a genuine emergent-strategy thrill to deciding whether to prioritize a ring of spike-launchers for offense, a cluster of movement zooids for hit-and-run mobility, or a defensive shell that lets you bully your way through everything. Because parts are positional, where you place a zooid matters as much as which one you pick. A poorly balanced creature spins uselessly. A well-designed one carves through the ecosystem like it was born to.

The second game is combat and survival, and it’s merely fine. Fights are physics-flavored scrums—you ram, you fire, you retreat—and the design aims for a loop of eat, grow, repeat. But the tactical ceiling is lower than the building system deserves. Once you’ve assembled a build that works, encounters stop testing you. You’re not out-thinking rivals so much as out-massing them. The escalation that made agar.io tense—that constant vulnerability to something bigger—softens here, because your carefully engineered organism is usually the biggest thing in the pond.

Where the Structure Cracks

The campaign is Sipho’s weakest limb, and it’s not close. Procedural generation is a double-edged blade: it promises infinite worlds and delivers repetition dressed as variety. The “endlessly varied ecosystems” are, structurally, the same few encounters reshuffled. Enemy variety is thin. The hostile life you’re devouring rarely forces a rethink of your build, which is a real failure in a game about builds. When the enemies don’t demand adaptation, the deepest system in the game—creature design—stops being a survival tool and becomes decoration.

This is the central tension of Sipho, and it’s worth sitting with. The developers built a magnificent sandbox and then bolted a mediocre obstacle course onto it. The onboarding compounds the problem: the game explains its parts but not its possibilities, leaving new players to bounce off the complexity before the “aha” of a working creature clicks. Sipho asks you to fall in love with experimentation, then gives you a campaign that punishes it less than it should reward it.

The Aquarium Redemption

And yet. The Aquarium flips the whole calculus. Stripped of survival pressure and resource gating, Sipho becomes what it always wanted to be: a toy. Here the unlimited tools let you stage creature-versus-creature battles, design absurd body plans purely to see what happens, and treat the physics system as a canvas. It’s telling that the sandbox—the mode with no goals—is more compelling than the campaign built entirely around them. That’s a design verdict in itself, and not a flattering one for the rest of the game.

Aesthetically, Sipho commits to its concept with admirable nerve. The art direction leans into the eerie beauty of the abyssal deep—your creatures are pale, twitching, faintly grotesque assemblages that look plucked from a marine biologist’s nightmares. It’s a look that could have been cheap and cartoonish; instead it’s specific and slightly disturbing, which is exactly right for a game about colonial organisms. The clean, readable presentation keeps the on-screen chaos legible even when a dozen zooids are flailing at once.

Technically, a 2D game of this scope is light on hardware, and the modest presentation suits it. The UI, though, is the recurring pain point: the construction interface is functional but not intuitive, and managing a complex creature’s parts is built in a way that gets fiddlier than it should as designs grow. For a game whose entire value proposition is building, the builder’s interface friction is a self-inflicted wound.

On Steam with mouse and keyboard, Sipho is in its natural habitat. The construction system demands precise placement, and the mouse handles that with the accuracy it needs—clicking, dragging, and rotating zooids into position is where the input shines. Combat, being physics-driven rather than twitch-precise, doesn’t demand a keyboard, but the workshop-heavy nature of the game means keyboard-and-mouse remains the definitive way to play. This is a desk game, not a couch game.

Sipho is a brilliant idea in search of a game worthy of it. The zooid system is a small triumph—a modular, emergent, and original take on the creature-builder. But the survival scaffolding around it never rises to meet that ambition. The campaign repeats itself, the enemies don’t push back hard enough, and the interface fights you more than the wildlife does.

What saves it is the sandbox, and what recommends it is the concept. For the narrow slice of players who read “build a monster from specialized living parts” and feel a spark, that spark is real and Sipho will feed it. For everyone else, this pond is shallower than it looks. A charming, singular, flawed creature—hard to recommend at full price, and only worth adopting for those who already know the workshop is where they plan to live.