Hi silversatyr!
Thanks for the lets play of our game, we're sorry you encountered a game crashing bug :( we'll add this to our bug fix list and work on it straight away to fix it ready for the version uploaded after the competition. (for reference if you play again, there is a save point before each boss so if you die you won't lose a ton of progress).
We're glad you like the premise and aesthetic, we were hoping to add more to it to stand out more from it's inspirations but we didn't have time.
Also, it could be explained better in the battle tutorial (the whole tutorial we want to move to an in battle segment anyway, but that's for another time) but you can choose cards as soon as the blue bar is filled at the top and you can select multiple cards at a time to use multiple skills between bar charges. This'll make battles a bit more interesting instead of just the basic attack.
Again, thanks for playing :D