bugs - when last enemy remains the game gets stuck (at the moment when you attack the last remaining enemy).
mechanics - the grid turn-based mechanics works well functionally, but its not yet exactly clear what is happening. I noticed that you can reset movement range of the hero after switching between movement and attack - not sure if that was intentional. Also, I couldn't understand what is the loop of movement and attacks in general. But given that it is at the early stage of dev looks like a good foundation you have there already (mechanics-wise).
grid movement - feels great and clear!
in general I like the idea of moving around the hex grid with a set of heroes that have their unique abilities.
Great start!