There are two versions. The old and the new.
To lessen the confusion, I'll rename the old version on iOS to "The Quest Classic" and "The Quest HD" to simply "The Quest" (whenever I'll have time
). On Steam and on Android only the new version is available.
Here are the major changes in the new version:
viewtopic.php?f=41&t=4204#p11529 (Basically, it's the same game. The only major changes are in the expansion, Islands of Ice and Fire, where the main quest line has been reworked and there are a couple of new quests added.)
No expansions are included.
All guides should work (except as noted there might be some changes to Islands of Ice and Fire, however those should make it easier to follow the game).
Robot Oil is only found in Zarista Games' expansions (no idea which ones). Also there are no permanent potion recipes in the base game.