FAQ

Is this a game engine?

No. PWE is a substrate: a microkernel runtime plus a language for deterministic, distributed simulation of a 4D world. It happens to ship a live 3-D viewer so you can watch what you modeled.

Why a language instead of a scene description?

Because the interesting cases are not a fixed set of behaviors you configure — they are equations. slot = expr means slot += dt·expr; rk4 integrates the same rules at 4th order. Chemistry, acoustics, robotics and population dynamics use the same language, only the equations change.

How is determinism proven, not promised?

• The interpreter is the semantic reference; the JIT must produce byte-identical writes and identical event/queue streams on every step (step_cross).
• Every simulation is checked against a closed-form solution (Newton cooling, Kepler orbits, radioactive decay, …).
• State hashes reproduce bit-for-bit across runs and snapshots.
• The conformance suite runs with zero skips.

See Determinism.

What does .pweb mean?

A self-describing, verified binary artifact — the analogue of .class for java. Compile once, then pwe run / pwe present execute the compiled EIR. Recompile and you get the same bytes for the same world.

Does it need a GPU?

No. The reference implements the interpreter (the oracle), the interpreter-backed JIT, and the AOT path — all differentially verified on CPU. GPU / NPU / SIMD plug in at AotProgram.target and are on the roadmap.

Is it distributed?

Yes, by design: exactly one authoritative owner per mutable entity, an ownership state machine with epochs that reject stale commands, and replaceable transport (QUIC initially). Split-brain authority is never silently allowed.

What does "4D" mean here?

3D space plus time — with time explicit and domain-based. Grid fields are volumetric, so a field with depth is a 3-D continuum evolving on the step clock: a 4D substrate.

Can I override physical constants?

Yes. Standard-library functions are keyed by namespaced constants, overridable with --param against the same artifact — no recompile.

What are the honest limits right now?

• The reference "JIT" locks the JIT contract; it does not yet emit native code.
• Rigid bodies cover AABB, sphere, convex-hull (exact SAT), compound and heightfield colliders, impulses, friction, distance joints and a ground plane — see RFC-0039 and RFC-0040 for joints and soft bodies.
• Rendering is a first-class peer domain consuming a RenderView, but there is no offline renderer.

The live assessment lives in Review & roadmap.

Where do I start?

Quick start — build, test, and run a world in under a minute.