Play mode

Press play, and your scene runs — physics, particles, keyframed animation, all of it live. Press stop, and it snaps back exactly to where you started, as if none of it happened. That reversibility is a deliberate design choice that makes experimenting with your scene safe by default.

Start and stop playback

Press Space, or click Play in the canvas toolbar. The instant playback starts, Formo captures a full snapshot of your scene's current state: everything about to be disturbed by physics, keyframed motion, or any other live behavior is recorded first, before anything is allowed to change.

Press Space again, or click Stop. Everything reverts to that captured snapshot, instantly and completely — a physics object that tumbled somewhere new, particles that were emitted, anything that happened purely as a result of playing, all discarded. Nothing sticks unless you specifically keyframed that outcome. This is what makes hitting play a safe way to just look at your work rather than a commitment: you can experiment as many times as you want, and stopping always puts you back exactly where you started.

Pause and resume the simulation

Play isn't strictly all-or-nothing: a Pause button in the play controls freezes the simulation mid-run without discarding it the way Stop does. Paused playback drops you into a state where you can select and interact with objects on the canvas while the simulation is held mid-motion, gizmos and all, rather than locking you out until you stop entirely. Click Pause again (or Resume) to pick back up exactly where it froze.

Step through the animation frame by frame

While paused, a Step button advances the simulation forward exactly one frame at a time. This is the precise way to inspect what a physics interaction or a keyframed motion is doing moment to moment. Rather than watching it happen at full speed and trying to catch the detail you care about, step through it one frame at a time until you're looking at exactly the moment you need.

Apply changes from the simulation

There's one way to make what happened during play permanent: the Apply button, available while paused. Instead of discarding the current mid-simulation state when you eventually stop, Apply bakes wherever everything currently sits — including whatever physics settled into — directly into your document, as editable state going forward. This is the move for when a physics simulation lands in a pose or arrangement you actually want to keep, rather than something you're just previewing.

Work non-destructively in Play Mode

One caveat: Apply is recorded as an action in your undo history, but that specific action currently can't be reversed with Ctrl+Z the normal way. This is a known, narrow limitation rather than the general rule. Everything else about Play/Pause/Stop remains fully safe to experiment with; Apply specifically is the one deliberate, harder-to-take-back step in the whole system, by design, since its entire purpose is making something permanent.