I may be off topic or misunderstanding the question, but apps wouldn't be on my essential list for <i>real life extreme situations</i>.<p>I'd say physical fitness: the ability to lift things, pull one's own weight (not bench press an equivalent mass, but actually pull one's body over obstacles): chin ups or equivalent. Jump, grab wall, pull body over wall, get to the other side.<p>The ability to run fast for a period of time. The ability to run at moderate speed for an extended period of time. The ability to walk for a long period of time. (real life situation: noWhether we like it or not, if we don't have these we're more like a burden and rely upon those who love us to survive.Whether we like it or not, if we don't have these we're more like a burden and rely upon those who love us to survive. transportation and no comms, shrug it and walk 20 miles during the night to get home).<p>The ability to lift someone and walk/run with them.<p>The ability not to eat for extended periods of time without panicking or going insane (i.e: not needing to eat every couple of hours, or three meals a day or becoming intolerable). Does help to have gone a day or two without eating before just to know one can do it.<p>Basic self defense (hand to hand).<p>Knowing how to handle firearms helps (safety, clean, disassemble, reassemble). Shooting right helps.<p>"Survival stuff" (ability to make fishing instruments with basic items, traps, etc. Ability to skin animals helps). Being handy and resourceful in general (good with hands, manufacturing things and tools, fixing stuff).<p>Having stashed or acquired valuable things to use to buy things or barter.<p>Mental resilience, morale control, positivity and determination, and the ability to radiate this onto others help tremendously.<p>In the absense of these, we are a burden and depend on those who love us, appreciate us, or just are in a good mood for our survival.