Walkthrough: the Chapter I route
Chapter I runs from the starting shelter to the Sphere, then the vortex. No official source publishes transmitter-puzzle solutions, but the October 1 and October 4 patches fixed the navigation and softlocks that stop the route.
RADIOSOL never hands you a quest log or an objective marker, so a walkthrough here means the route the game pushes you along, in the order its own achievement data lays it out. What follows is that route, the places it passes through, and the fixes the October patches shipped. No room-by-room spoilers, and nothing invented to look complete.
The route starts in shade, under architecture big enough to block the Sun.
What this walkthrough covers, and what it leaves out
RADIOSOL has no combat, and the developer has said plainly that "searching every inch of the map isn't required to progress". So this is routing rather than a strategy guide: where the game sends you, which blockers have been patched, and which items are optional. Interior puzzle steps, terminal text and the story's final beats are deliberately left out — the endings page covers the finale separately.
The critical path, in the order the game reveals it
Steam's global achievement rates are the only public, objective picture of the route's shape, checked October 5, 2026:
| Stage | What fires it | Players who reached it |
|---|---|---|
| Enter the simulation | You start playing. | 100% |
| Leave the starting shelter | You step out into the open. | 90.6% |
| Die from the sun | The Sun gets you at least once. | 63.1% |
| Almost die, but not | You survive something that should have finished you. | 34.0% |
| Power up the sphere | The Sphere is the story's engine, not a collectible. | 13.3% |
| Face the vortex and survive | A set-piece that sits after the Sphere. | 2.6% |
| Find all Calypso 5 | Five named collectibles, all of them. | 1.2% |
| Fly 10,000 km | Distance travelled — the long tail. | 0.2% |
Two things stand out. About two-thirds of everyone who installs RADIOSOL dies to the Sun at least once, so the survival layer is real. And the fall between "Power up the sphere" (13.3%) and the vortex is steep: only about one player in five who reaches the Sphere carries on through it. If you are stuck before the Sphere, you are where most of the playerbase is.
The places the route passes through
- The starting shelter. Leaving it is the first real achievement, and the tutorial text was rewritten days before launch (September 22 patch). Read it: it explains how the Sun kills you.
- The Sphere, and its entrance. Where "Birth" fires. The October 1 patch fixed a softlock that trapped players who left through the same route they entered.
- The Service Depot and the districts. Named in the October 1 navigation pass; district names now show on every visit, and October 4 added more geographical hints. Quote the district when a route blocks.
- Megapol. The city-scale ruin whose lobby was still being modelled on September 22; the story page covers the name.
- The vortex. The post-Sphere set-piece behind "Let The Tempest Come Strike Harder".
- Calypso 5. Five collectibles, tracked by one achievement that fires only when you have all of them.
Navigation fixes since launch
October 1 patch: cardinal-direction hints and the marker-button prompt corrected; the Sphere exit softlock fixed; navigation to the Sphere entrance and the Service Depot improved; district names shown on every visit.
October 4 patch: several frustrating ambiguities resolved, more geographical hints, triggers widened, and fixes for a digital signature softlock, a damage-saving bug, a life support core bug, a run/step animation bug, several traps, colliders and sounds, and interrupted downloads.
Radio markers are the one navigation tool the game gives you outright: since September 22 they persist, so a marker dropped at a junction, tower base or entrance is still there when you return. They are not respawn checkpoints — nothing in the patch notes says markers save your position.
Radio, terminals and the transmitter questions
The radio network is both the story's voice and the game's memory system: markers are saved, and terminals deliver backstory as text rather than as a locked puzzle. Two things are documented here that are worth separating:
- Markers are saved. Confirmed in the September 22 patch notes. Drop them at junctions, tower bases and entrances.
- No official solution list exists. The developers have never published solutions for a signal or transmitter sequence, so this page will not invent one. If a step will not resolve, install the current build — October 4 widened triggers — and retry from the last district you entered.
Collectibles and the optional tail
- Files added to the world (September 22 patch) — documents off the main path. Nothing on the critical path depends on them, which is the point.
- Calypso 5 — all five, at 1.2% of players — and 10,000 km travelled at 0.2%. The world keeps going long after the story stops requiring it.
The critical path is a fraction of the map; the rest is files and distance.
Sphere, vortex, then the story's handoff — what Chapter I resolves is on the endings page, and the beginner guide covers the first hour.
