Both Lies of Astaroth and Elemental Kingdoms run on my iPad, and I tried both to see what they were about. LoA has more cutesy graphics, while EK has more of a high fantasy style. Cards names and images are different, and so are the maps and other images in the game. But apart from that graphical difference, the games clearly work on the same game engine, with every single UI element being exactly in the same position and doing exactly the same thing in those games. I couldn’t check Elves Realm, as it apparently is only available in some Asian iTunes stores, and the Google Play version isn’t compatible with my smart phone (presumably it needs an Android tablet). But as far as I could see from a YouTube video, it actually is exactly the same game with exactly the same cards and graphics as Lies of Astaroth.
Apart from the clone weirdness, I kind of like Elemental Kingdoms. A collectible card game consists of a deckbuilding part and a playing part. Both were equally important and challenging in Magic the Gathering, which I liked a lot. In Hearthstone the deckbuilding was much less important than the playing, and I couldn’t warm up to that. In Elemental Kingdoms and the clones, deckbuilding is far more important than playing. In fact you can do most battles by pressing the prominent Autoplay button. But the deckbuilding is important, as you get very few cards in a deck, start with only 1 card in hand, and draw only 1 per round. While the random order in which you thus draw the cards can make a difference, it is extremely important to have built the best possible deck for the situation, especially if you want to beat the special conditions of the harder difficulties.
Other than that the games suffer from the same problem as every other collectible card game: It is kind of pay to win. Yes, you probably could get all cards from playing endlessly, but the temptation to spend money on boosters full of cards is great. But if you can live with that, Elemental Kingdoms is fun enough for a free to play mobile game. If you want to try it out, you can use my invitation code of 44vhwv (you enter that when you choose the name for your character).