Tutorial is kinda brief, you leave players to themselves in some of the game's aspects. For example, just one lil tutorial window about 4 top-right buttons. But "tech-tree" is very important part of your game (which isn't that much "idle", i'd say, because there is a complex system of bonuses to learn, which you also don't mention). How about after players place 2 earth tiles on the grid, tutorial window suggests to push the tech-tree button, where they can atleast get an idea what exactly they need to merge to progress. Because at first try i got 1 stone tile, and 0 production, so i thought that i'm "stuck". Maybe in next version you'll add to some tiles which are currently tech-only, some production aswell ? Oh, and why element "air" isn't in the game? Wind spread seeds... Also, shouldn't merging desert with water create an oasis? )