Thanks for the feedback, fren!
I'm glad you made it without a tutorial, because even though there's the how to play page, a proper tutorial should be in place, and it will be sooner rather than later (hopefully).
The point of saving mana is to use it during your opponent's turn, but saving it any further has no point since it regenerates at the start of your turn.
Hovering on cards and the sorting you mention is set on a timer on purpose, I found that having it change instantly felt janky to me, but some people have complained that it takes too long right now, so I'll tweak that.
Only seeing a the top part of your cards is also designed that way on purpose (sort of) because having your entire hand up all the time is a bit too clutter-y and I rather have a cleaner field of view and then check cards when I have to rather than not having the option to have them tucked away. I said sort of because due to how big I made everything I have way less visual real state to spare, so yeah, that's a design flaw that I have to address at some point but that I'm dreading. So yeah, I'm counting on the memorization of cards that you mentioned for now.
The cursor error is there because right before uploading the latest available update I did some major code cleanup and with the unnecessary stuff I also removed that cursor.visible=true, it will of course be fixed for the next update (A big one, btw)
Again, thanks for playing and thanks again for the feedback!