Crashlands Cat Quest Terraria (sort of) Battleheart Legacy Shadowrun Dragonfall Titan Quest It kind of depends on how open you want the world to be but all f those are not level based and give you freedom on where you want to go.
I'd definitely take Battleheart Legacy and Shadowrun Dragonfall off the list. While both are fantastic games (and should be in any mobile RPG gamer's library)' both are MUCH more linear in scope/and confined movement.
The Quest It's not for everyone, but is completely open-world, fairly non-linear and has many ways to play through it. Not as hack-n-slash as it looks - there is a lot of story/progression in addition to crafting, item/skill improvements, etc. Also the HD version is a real treat!