Fall of Angels has a similar puzzle solving world exploration vibe as original Fallouts albiet not in a postapocalyptic setting and sans water crystals. Xenome has a similar setting as does Phantasy Star II (JRPG) and perhaps Steam Pirates (on my "to play" list). I haven't gotten around to Alternative Reality The City / The Dungeon but those also show promise in terms of exploration depth.
AppStore definitely needs more steam punk. If you play PC games there was a Fallout era game called Arcanium that's worth loading up if you can find it.
Yeah, I think Arcanium was made by former Fallout devs (Troika). Might also want to check out Wasteland, made by Brian Fargo before Fallout. He just got a ton of money on Kickstarter to make Wasteland 2, so keep an eye out for that.