Great Game! I love the strategy and how much you have to think ahead. My only complaint is readability. A few points to that:
1. As cool as the suit art looks, it's rather difficult to tell what suit a card is at a glance, even more so when there are a lot of stickers on a card. The flow of the game is interrupted when you have to stare at a card for several seconds to figure out what suit it is. This is especially annoying when the suit plays such a big part in the game with the green/red diamond stickers. Also, if you are going to use non-traditional suits like the sword or gold, a reference for the player to understand these suits is going to be a necessity. (Think a label for the name of the suit with an example image next to it.)
2. The stickers are a little bit big for the card face, and it leads to a cluttered mess when trying to figure out what a card is capable of. Since the player can already hover over a sticker to see what it does, I think reducing the size of the stickers would be a good change.
3. Overlapping stickers are another readability problem. Unless I am mistaken, I don't believe there is an intent to hide information from a player about what the opponent's card will do. When stickers overlap, it becomes harder or even impossible to hover over them and determine their function. Not to mention being unable to clearly determine how many stickers a card has for the effects that care about that.
4. The draw and discard piles could be labeled. It might not be an issue for everybody, but I'll admit I didn't realize what they were until the third opponent.
Beyond that, this is a really cool concept that was enjoyable to play! Good luck with the future of this project!