In Vessel's alternate universe of gushing smokestacks and spinning cogwheels, industry has been supported by a single inventor – you – and your world-changing creation: the fluro. These semisentient servile beings coalesce from available liquids, and have an often self-destructive desire to jump on large red buttons.
A laboratory mishap reveals their many and varied adaptations, which turn out to be handy for solving the throw-switch and pressure-plate puzzles of this 2D platform world.
A supply of fluro 'seeds' enables you to conjure these critters wherever you choose. Drop one, douse it in water, lava or even fruit juice, and a gormless helper will arise. Different seeds provide fluros of different behaviours. Some are fixated on button pushing, others chase you or seek out light sources, and still others look for liquids matching their constituent mass and slurp them until they burst. Environments often have grills through which only fluros can pass, so much of the game involves working out where to place a fluro such that it gambols through a run of switches in the right order while pursuing the appropriate behavioural goal.
It's a nice enough trick, and repeated in many guises with clever complications: lava fluros and water fluros can be coaxed into collisions, activating steam-powered contraptions. Fruit-pulp fluros grow on trees in two flavours – mix them and they detonate. The emphasis on fluid dynamics means occasionally adjusting the angle of a spraying nozzle, or thinking carefully about where you are going to squirt your own canister-supplied hose.
There's often a platforming or timing element to these otherwise gentle intellectual challenges, and this is where the game comes a little unstuck: movement in this world is awkward, your character's gangly marionette body snagging on some things and sliding off others. The graphics have a stunning gloss, but it doesn't help in differentiating background detail from foreground collision object.
Nor are the fluid dynamics, physics and AI behaviours quite reliable enough in their simulation to deliver satisfyingly pat results. Some solutions end up an ugly, frantic fudge, or jeopardised by some random spasm of fluro whim. The swooping, zooming camera doesn't help, often truncating useful information, erasing off-screen fluros from existence, or simply pulling out so far that the game sputters into super slow-motion.
But if Vessel's action is sometimes shabby and erratic, at least the fluid simulation is a real novelty for this genre. Every now and again, those dynamic elements come together to deliver a solution that rivals the “Eureka!” moment of any other puzzler. Despite its occasional chaos and fussy foibles, Vessel's central gimmick just about holds water.