My impression is, you had a cool idea - i absolutely agree! And you realized it - which not everone achieves, so honestly: patt yourself on the back, really. You also layed the foundation would could become a cool game, for instance: there is skills, pieces, you can select them (card-like interface at the bottom) etc. All you need for the mechanics. Even the music is there, and I like it - very relaxing and still stimulating with a rich melody. Well chosen! I have some issues with the game, though:

What I don't get is why you have to select move versus attack. The pieces work like in real chess, so, there is no need to let the player have to click on attack versus move. Selecting a piece and the destination should be enough, because empty tile -> move, opponent there -> attack.

The health bar is a valid idea, but I must admit I don't like it at all, because it breaks all the strategic fun of the game - BUT: this is just MY opinion. I might include a health bar only for exceptional cases, i.e., all pieces have only 1 HP (not 4 HP) per default, but some skill (or neighborhood to some other skillful piece) would extend this pieces HP from 1 to 2 HPs. In that case, this piece is in an exceptionally healty state, and then the HPs would be more interesting. Again: just my personal opinion. You don't have to agree. 

Pawn reaching the end of the board -> no conversion, that's ok, but then there should(?)/could be something else.

I saw a tile destroyer skill, but I was not allowed to use it somehow. Anyway of this issue, but hey, these skills sound like the real fun. Also make obstacles on the board, maybe randomly and also by the players. Also skills to transform tiles from ground to water and then allow some pieces to walk through water and other not. Stuff like this could make the RPG-ish chess more fun.

And yes, the AI opponent... woah, that is actually not easy to do well. This might become a hard challenge. But I agree with the Dragon... that in the current state the game is ways too easy and thus looses the challenge and fun to play.

BUT, as I said at the start: I like the idea und you laid the foundation for making a cool game. Keep the motivation and experiment with the potential you have. Looking forward to next versions. You can use the TheWoodlander's discord server to inform us and discuss with us.

Starting the game, it feels like parts are cut off. The hearts at the top were cut off slightly, while the bottom ones go right up to the edge. Switching to fullscreen, the top hearts go to the edge, and the bottom ones are cut off at about the half way point. Exiting fullscreen the blue hearts moved up a ways to be next to the bottom right corner of the board. I could also now see the top of the Pawn card, which had previously been off screen.

I used summon to place a Pawn. It then went back to the bottom edge so I could just see the name at the top and a little more below it. Summon was greyed out. I moved my Pawn across the board and the opponent avoided it. It got to the end and then seemed to be stuck. I used my King to get close to the opponent and was able to beat them, though it was just a matter of whoever struck first won.

I picked a new piece and the next round started with the cards off screen again. Clicking on Summon brought them up.

The CPU is not very smart. They often moved into positions that let me attack them. The Queen gave me some trouble due to her power, but I had 2 Rooks. I lost 1 to her, and the other was at half health. Then I faced their Rook. I got into position and attacked them. Instead of striking back and finishing off my Rook, they moved away. I moved my King up slowly, as they moved back and forth across the top row. When my King was 1 row from the top I moved diagonally near their piece. They moved down 2 tiles, remaining in range of my attack, allowing me to end the fight with my next move.

The game could use with some basic instructions, even if just on the game page. The enemy logic could use with being less suicidal, though I do acknowledge that with so few pieces, and your starters being slow to move, it could be a long game of chase if they were too smart. The Pawns being unable to upgrade, or do anything, once they reached the other edge was an unpleasant surprize. It would be nice if they could upgrade or do something more at that point.

It's very intuitive because it's played with classic chess pieces; yet mechanics like piece health, movement limitations, swap etc. successfully keep it interesting. Also, I've encountered a bug with the summoning mechanic, where the animated piece card is not always selected correctly.