Good start for a game.
I just wished that there was a way to see your stats (current HP, number of cards, attack and healing bonus) in the battle menu and the level selection menu.
Also, I had a run where the first level was a healing one, which didn't do anything, maybe try and have so that the first level can't be a healing one.
I really hope the game development continues and ends up being a full game, I think it really has some potential !
PS: I'd have a few other minor complaints, but I think that most of them are due to the working in progress nature of the game and that the dev knows about them, so I won't make a list here (unless the dev explicitly wants me to, I guess.), to not sound to demoralizing or negative.
Most of the issue I have are not really bugs, more like edge-cases or "oops, I forgot", like how I ended up having three healing level back to back on a single line (It was the only level I could choose), which was both useless since I was already healed, but coast me the run since I couldn't upgrade my character because of it.
How the settings menu does nothing, (which is okay if you haven't worked on it yet,) but just adding a message saying: "coming soon" would be great, because I was very confused for a minute about why nothing was showing up.
When I restarted a game after finishing my first one, the camera was at the end of the map, and not at the beginning (I think the camera position didn't rest from the last game)
The character on the title screens sometimes doesn't react to my mouse movement, before suddenly teleporting in the right place (this one might be an issue on my end)
A small detail, but when finishing a battle, if you choose to skip the H scene, the enemy battle sprit stays in the background while you select which upgrade you want, but if you chose to see the H scene, the character art disappears while you chose the upgrade. It isn't really an issue, but it is inconsistent between the two: I (, and this is only my opinion,) think that you should either display the defeated enemy in the background of both, or not show the enemy at all while selecting the upgrade.
That's all the issues I found while playing, but I want to stress that the game was fun and enjoyable, I am only writing and criticizing this much because I think this game has the potential to be very good in the future.
I am cheering you on, don't take it the wrong way.
On that note, I hope you found all of that useful and bye :]