The game really needs more explanation as it doesn't seem to make much sense if you just go and try to play it. How the cards relate to the game play and the difference between gems and crystals and gold and upgrading and stuff should all be explain before you start playing.
You cant use Gems yet. so Basically no one knows for sure beside Jasper what are they for. Game is not finished. That si a big disappointment i got. But generally, when i made new account to play from start without any blockchain cards. Is really fun to play first 2 days.
My disappointment is that I expected game and all around will be finished. Like it would be real release yesterday. So from now on would be only polishing bugs. But now whole parts of game are missing and I see was already soem changes from yesterday. So my speculation is that there will still be a so called Soft Launch when all stats will reset wand we will be able to test full game fro a week or so before Full launch.
Ok so you can't use gems or blockchain cards or bitcrystals, that's understandable. But I can't even see at first look what the in-game cards do. I can't see any difference between one or the other - all I can see is that you point at a ball and click. There is no explanation of the gameplay at all, if there actually is any beyond clicking a ball.
You can normally use blockchain cards. I personally made new account to experience how new players see the game. And on this new account i dont have any blockchain cards.
To see your cards and their strength you go to team page, then double click on a card:

This card adds 1 speed you see in top right corner. It has 1 strength and 8 health. Yellow and red ball under the picture. It also have a spell Flame, that hits with 2 strength.
But generally you are right. Game needs more explanations. At least at first Campaigns. Since si expected that are made by totally new players. So explanations pop up while doing first campaigns. Also there could be some text when you hover Achievements. To understand what that achievement is for and how to achieve it. Maybe also for other things to better understood by new players.