Survival Manual based on the Army Field Manual 21-76 - fully working offline. It contains info on how to make fire, build a shelter, find food, heal and other useful content in a case of emergency. But it does not have to be used in emergency situations only - it can be also useful for trips to the outdoors, hiking, camping, learning about nature and yourself truly. This is not only fun, but you can also train skills (make fire, build shelter, ..) you might need in a catastrophy. Some things work best with practice in a relaxed environment - then you also have time for some experiments.