I’ve been with friends in the woods twice since last fall when someone broke a chain. Fortunately someone had a chain tool but it’s something I’ve never thought about. On my road bike, it’s no problem; you just call for a ride, but in the woods, it’s not that easy.
Topeak’s ALiEN III looks like the perfect tool for that repair along with anything else that can happen when you “go deep” in the woods. While I haven’t seen it in person, it looks pretty good according to their site.