We currently have quite a long list of improvements we'll be making, based on things we didn't have time for and feedback we've received. I figured I'd post some of what we currently have planned for anyone who's interested (subject to change). 

• Boss health bar display, better visualization of enraged status
• Create short cutscene when entering the boss room
• Improve environment graphics and details
• Tweak basic enemy AI and settings
• Display stroke count total at end of game
• Fix some issues with attacking feedbacks
• Add a simple mini map display to illustrate how close you are to the boss level
• Add some quick pop up tutorials/tips at the start of the game
• Add more songs to play throughout
• Add post processing effects

There are some other smaller things we're also planning to add, but this is more for the interesting stuff.