Oberth

You fly a cargo pod with one button.

Hold it. The pod throws a tether to the nearest body and locks into a circular orbit — and the tighter and deeper it swings, the faster it winds up.

Let go. The line snaps and the pod leaves along the tangent, carrying every unit of speed it just earned.

That is the entire control scheme, and the entire skill. Where you press decides the circle. How long you hold decides the speed. When you release decides everything else.

It is named after the Oberth effect, which is real orbital mechanics: a burn made deepest and fastest inside a gravity well extracts the most energy out of it. This game is that sentence, played.

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The rope changes everything

Half the campaign asks you to fetch something. Cargo rides on a tow-line behind you — a real spring, not a rigid stick — so it lags, it swings wide, and it arrives at every corner a moment after you do. A loaded pod winds up slower and turns worse, and a load that clips a mine shears the line and drifts home, which costs you the trip back.

Learning to fly is one thing. Learning to fly with something heavy on the end of a rope is the game.

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What's in it

• 72 levels across 12 sectors — anchors that run out of hold, fields that push and pull and drag, rocks on rails, doors that refuse you if you arrive too fast, and anchors that slow you down instead of speeding you up
• Time attack — every level has a par time and bronze/silver/gold medals off it, plus badges for clearing under a tether ration
• A secret one for a level you have cleared without ever dying on it. It is not advertised anywhere in the game and it is never taken back
• Instant retry — hold the abort target for half a second and you are back on the pad. Dying is meant to be cheap
• No randomness at all. The simulation is deterministic to the fixed step, so a level is never a lottery. Every death was yours and every route is learnable

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About those par times

Each level is flown thousands of times by a bot that searches for routes, and the par is set from what it finds — but only from a route that survives being mistimed by a fixed step or two. A line that only works if you release on exactly the right frame doesn't get to be gold.

It also means every level in this game is proven to have a way through, and proven to have one a person could actually fly.

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Where this is going — so nobody is surprised

OBERTH is in development, and free while it is.

The finished version is going to Android and iOS, and possibly Steam, and it will cost money, with the first two or three sectors free as a demo. When that happens, the build on this page becomes that demo.

I would much rather say this now than spring it on anyone later. If you are playing it here, you are playing it early, and that is the deal: it is free, it is not finished, and what you tell me shapes what it becomes. Play it and tell me what you think, and I will look after you when it launches.

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Not in yet

Being honest about the current build so nobody has to file a bug for it:

• No sound. It is coming, and it is the next thing after this playtest
• No ghost replays or leaderboards. The game already records every run as one bit per frame, so these are close — they just aren't in yet I'm considering leaderboards.
• Play it on a desktop for now. It runs in a phone browser decently well, but not superb; a proper mobile app is on the way and will be a much better version of this

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Controls

One button. Space, left mouse, or touch — all three do the same thing, because there is only one thing to do.

Hold the abort target in the corner for half a second to restart the flight, or keep holding to leave for the sector map. Tap the pause target to stop and think; the clock stops with it, because you cannot fly better by panicking.

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Tell me things

This is a playtest and I am reading everything. Especially useful:

• a level where you could not work out what was being asked
• a death that felt like the game's fault rather than yours
• anything on screen you could not read at a glance
• the level you gave up on, and roughly how many tries in

Comments here, or the devlog.