This is a great start. I really like the tactical combat approach to the gameplay, and I also like that your hand is use it or lose it - drawing a new hand every turn is a good way to prevent unneeded cards from piling up and encourage making the most of your options each turn. The relaxing music is really nice.
One thing that annoyed me a bit is that there are no options for attacking diagonally, other than Tremor. There are three attacks that can only target two axes, and the cone attack even has gaps along the diagonals. Is this intentional? If you are planning to have multiple characters later on, this could make sense as a weakness of the golem character. For now though, it makes lining up attacks a little bit too finicky. There were many turns where I just couldn't quite target anything nearby.
I also had some bugs with input. A minor one was that there was one stage where the map wouldn't come up, but the bigger issue was that when I reached the last stage on the map, my mouse input got scrambled. It accepted a right-click, but I couldn't click on any cards. This actually resolved itself after I ended my turn, and I was able to play properly starting on my next turn.
There are also some issues with the menu. Sometimes the buttons do not register the pointer position correctly and can't be clicked, but I couldn't tell what exactly was causing this. The mouse events also carry through the menu and into the game. This means that you can toggle movement mode while in the menu, and, if you are in movement mode, clicking a menu option will submit a movement command to that position on the screen.
One thing I wasn't clear on was how exactly turns work. I figured out that your remaining turns carry over between rooms, but how many new turns do you get? Does it depend on the number of enemies? Also, you can spend more turns at the end of a stage than you have available and go to zero or negative (before the new turns are added) - is this intended?