Try it first: free playable Windows demo, no Unreal Engine needed. Drop, hit, slice and absorb slime, honey, jelly, tar and mercury, watch blobs merge and colors mix, and see the live simulation and surface timings: https://drive.google.com/file/d/1rog9NqqMhEUpeBs4PQvXd_jOmbhUJKlL/view

Coalesce gives Unreal Engine 5.6 - 5.8 real-time goo: blobs that melt together when they touch, stretch into strands that thin out and snap, split when you cut them, and come back together. Slime, honey, tar, jelly, mercury and water presets, or tune your own: viscosity, surface tension, elasticity, flow, stickiness, friction.

Everything is our own code: no Niagara Fluids and no engine distance fields. A particle simulation with strands that flow and snap, and a surface builder that only visits the space near the fluid, puts every vertex on the exact surface with an analytic normal, and reuses the parts that did not move. Both run on worker threads.

For gameplay

• Spawn blobs and drops, hit them, blow them apart, pull them, slice them, absorb them.

• On Blobs Merged / On Blob Split events with stable blob ids: slimes that split when hit, enemies that fuse.

• Sticky fluid that clings to walls and hangs from ceilings, drips, rides moving platforms.

• Two-way physics: the fluid pushes crates and balls with its real weight (measured: 100.0% of its weight).

• Several fluids in one container: colors blend where they merge.

• Emitter component for taps, leaks and slime cannons.

For art

• Place blobs in the editor and watch them melt together; bake the result to a Nanite Static Mesh in one click.

• Any material: fluid color in vertex color, world box-projected UVs. Glossy subsurface, metallic and matte materials included.

Measured (i7-14650HX, UE 5.8; from the included automation tests and benchmark)

• 1,000 particles: about 4 ms simulation per 60 Hz frame and 4.5 ms surface (medians), on worker threads, not on the game thread.

• Surface building vs the classic metaballs method at the same resolution: 10x faster at 32-128 balls, 61x at 512, 93x at 2,048.

• Exact surface: worst vertex error 0.0001 cm; closed meshes; deterministic on one machine.

Limits

• A viscous-fluid and blob system, not an ocean or river simulation.

• Not replicated (deterministic on one machine; drive it from replicated events in multiplayer).

• The live surface is a dynamic mesh; baked meshes use Nanite.

C++ source included. 12 automation tests. Blueprint-ready API. Windows (Win64).