Really cool game! It's so pretty—the visuals remind me of Tron and the music helps you get into the zone. The roguelike progression system with choice of upgrades is pretty fun too.

Some suggestions if you're open to them: I know the upgrade screen is integral to the gameplay, but it really stops the flow of the game. I feel like your game wants to be a game where you get into the zone and can go for an hour if you get really good at it, but the upgrade screen works against that goal. I'm not sure what the solution would be, perhaps having realtime upgrade screen that doesn't stop the action?

This goes into my second piece of feedback which is that I think the upgrades are perhaps too complicated. There's usually three stats being modified per card. Honestly, I would try cutting this down to one stat per card. Maybe have two rounds of card picks. One for the positive stats and one for the negative stats. That way the player can quickly read the cards, react and choose, without breaking the flow of combat.

Just some humble ideas. Cheers Darko!