The one number that made our survival game work
A game can be full of things that hurt you and still not feel tense. What fixed Castaway was a stat that makes your compass worse.
Castaway is a turn-based island game. You've been shipwrecked, three engine parts are somewhere inland, and the storm that wrecked you is coming back. Move a tile at a time, deal with whatever you find, and get all three parts back to the wreck before your food, your health or the weather runs out.
The first version had all of that and still felt like running errands.
Numbers going down isn't pressure
Health, food and a turn limit all ran down, and any of them could end the run. The trouble was that you could do the maths. Nineteen rations, thirty-two turns: plan the shortest route to the three parts and walk it. Danger you can budget for isn't scary. What was missing was something that made it harder to decide, not just more expensive.
Nerve, and a compass that lies
So we added a fourth stat, nerve. The only help you get finding the parts is a compass pointing at the nearest one, and the lower your nerve, the less accurate that compass gets. Nerve drains every turn you're away from the shore, and faster the further in you go. The beach barely costs anything. The ruins and the volcano cost a lot.
The longer you're out, the less you can trust the one thing telling you where to go. You're not solving a map any more. You're trying to finish before you can't read it.
The choice it creates
You can make camp: one turn and two rations to get some health and nerve back. And every few turns you face the same question. Stopping costs a turn you might need at the end. Pushing on makes the compass vaguer, so you wander, which might cost more turns than camping would have. There's no right answer, and that's the fun of it.
The storm has to be fair every time
If the parts happen to land close together the storm doesn't matter, and if they land in three far corners you were doomed from the first turn. So after an island is generated we work out the best possible route to all three parts and back, throw away islands where that's too long, and set the turn limit just above it. A perfect route always has a little room to spare. Nothing else does.
Hard mode doesn't add monsters. It gives you fewer turns, less food and faster nerve loss, so the compass goes bad sooner. Losing to worse information feels fairer than losing to worse luck: you pushed on with a compass you didn't trust, and you knew it.