What it is
One button, and then it plays itself.
Scrimshaw is an idle game. You start with a hull to scrape and nothing else on screen: one number, one button, one thing you can afford in about five taps. Buy the foundry and the ship starts earning without you, which is the point at which the game stops being about tapping and starts being about deciding.
Four things to build, and each one changes what the others are worth. Foundries make scrap. Reactors make power. Berths hold crew, and crew speeds up everything at once. The drive burns power to cross distance, and if you build more drive than reactor it runs at whatever fraction the reactors can feed, which you can see in the length of the exhaust.
The crossing
One light year, and then you do it again.
The voyage is one light year and takes a first-time crew somewhere around half an hour. Reaching the end is landfall: the colony is founded, and you launch the next ship from it carrying a permanent multiplier on everything. The second crossing is markedly faster than the first, and the one after that faster again.
Nobody aboard at the start is aboard at the end. That is the idea the game is built on, and it is also the reason the numbers reset while the charter does not.
How it behaves
Made to be put down.
It runs while closed, for up to eight hours. Coming back runs the same simulation the game runs while you are watching, second by second, rather than a generous estimate. The cap is there so that never opening the app is never the best way to play.
Every locked item says how long until you can afford it. Not a guess, the actual arithmetic at your current rate.
Nothing is explained up front. Power, crew and the distance bar each appear the moment you unlock the thing that produces them, and each arrives with one sentence. There is no tutorial to sit through.
Sound starts off. The haptics carry the feedback either way, which is the right default for a game people open on a bus.
Money
No advert you did not ask for.
The game is free. There are no banners, nothing between screens, and nothing that interrupts play. The only advert is a video you can choose to watch to double what you earned while the app was closed, and one optional purchase removes even that and grants the bonus permanently.
There is no account, no sign up and no server. Your voyage is a file on your phone and it is never uploaded. See the privacy policy for exactly what the adverts involve, and support for everything else.