Worlds
10 presets
From Solar System to Primordial Maw. Basic is quiet. Expert dies unless you seed gas, ignite and place wells.
Version 0.2
GSimuly Live gravity theater for iPhone and iPad
Watch a living universe.
Stars, planets and dust move under attraction, charge and wells. Change the laws. Listen as bodies graze, merge and are born.
Scroll
Theater is the stage. Setup is the workshop. Press play, pick a world, change the laws, and keep what unfolds.
How it works
-
01
Open Theater.
A universe is already running. Pause from the top left. Full screen when you only want the sky.
-
02
Pick a world.
Ten built-ins, from a quiet solar system to expert worlds that collapse unless you step in.
-
03
Use a tool.
Seed gas, ignite, place an attractor or a repeller, or trigger a nova. One tap on the stage.
-
04
Inspect, record, share.
Tap a body for mass, fuel and its note. Record a clip to Photos. Save a preset and send the file.
Watch
Live cosmic theater —
record and share.
Your film. Autoplay is silent. Turn sound on when you want the score.
The stage
Theater and Setup.
Two tabs. One is the sky. One is every law you can touch.
Theater
The stage. Play a preset, inspect a body, record.
Setup
Gravity, life, look, sound and export.
Tools
Watch, seed, ignite, attract, repel, nova.
Life
Fuel, accretion, supernova, collapse, rebirth.
On device
60 fps
Metal compute. No cloud. The governor caps node count to the device.
Sound
Live
Each shape has a note. Ambient loops under the sky. Collisions speak.
Your files
∞ upload
Stills and clips go to Photos. Presets you send are files you chose to share.
Made for
Watch, tinker,
or keep it alive.
Same app. Different moods. Start quiet, or pick an expert world that wants to collapse.
Basic
Sit with a sky
Solar System, Night Garden, Spiral Drift, Zen Constellation. Press play and watch.
Intermediate
A slower life cycle
Supernova Season, Twin Galaxies, Black Hole Bloom. Motion you can still follow.
Expert
Keep it from dying
Devourer, Heat Death Edge, Primordial Maw. Seed gas, ignite, place wells.
Listen
A score in the dark
Scales, per-body instruments, and ambient loops. Grazes and novas have a voice.
Record
Keep a clip
A still or a short video to Photos. Full screen if you only want the sky in the frame.
Share
Send a universe
Export a preset. Someone else loads it and runs the same world.
Version 0.2
The theater, and the workshop around it.
A body
Tap a star.
Change its mass.
Fuel, charge, pin in place, the instrument it plays. Heavier worlds swallow lighter ones on contact.
Setup
Every law
is a control.
Gravity, wells, palettes, shapes, scales, music, how long a recording lasts. Collapse a section, open another.
iPad
The same sky,
more room.
Theater and Setup on a larger stage. Tabs still sit on the left when you want the universe in front of you.
Before you start
Seven steps
in a universe.
Play. Pick. Touch. Keep.
- 01Open GSimuly. Theater is already running.
- 02Open Presets on the left and choose a world, or stay on Solar System.
- 03Tap a body to inspect it. Pinch to zoom. Double-tap to reset the view.
- 04On Tools, seed gas, ignite, attract, repel, or trigger a nova.
- 05In Setup, open Life Cycle or Gravity Wells if you want to rewrite the laws.
- 06Record a clip, or save a still from full screen. iOS asks once for Photos.
- 07Save a preset and share the file if someone else should run the same universe.
FAQ
Questions, answered.
What is GSimuly?
A live gravity theater. Stars, planets and dust move under attraction, charge and wells. You watch a small universe unfold, change its laws, and listen as bodies graze, merge and are born.
Do I need an account?
No. There is no account, no analytics, and no advertising. The last universe is saved on the device so it can resume.
Can I share a universe?
Yes. Save a preset from Setup or the library and send the file. The other person opens it with GSimuly and runs the same world.
Where do recordings go?
Stills and videos are added to your Photos library after you tap save. GSimuly does not read the rest of your library and does not upload those files.
Is this a science simulator?
It is for watching and playing with a small universe. It is not a research-grade n-body lab, and it is not a medical or navigational tool.
Which devices does it work with?
iPhone and iPad with iOS 17 or later. No Apple Watch. No account.
A theater, not a lab notebook.
GSimuly is for general educational and entertainment use. It is sold as is. Treat every orbit as a picture, not a prediction.
On the device
- No account. No analytics SDK.
- Presets and the last session stay local.
- Photos permission is add-only, when you save.
- The governor limits node count to the device.
Privacy
Nothing is sent off the device unless you choose to share a preset file.
GSimuly is provided as is, without warranties of any kind. For informational and entertainment use only.
Watch a living universe.
GSimuly. Live gravity theater for iPhone and iPad.
- iPhone and iPad · iOS 17 or later
- No account · no analytics
- Photos only when you save
- © 2026 Eyal Vardi