There is now an option to join the playtest on the Steam page - so press that and you'll be notified when it launches!
I'm pushing back the targeted start date to March 6th (apologies for the delay!), and it will last for a week. There's a few more features I want to add / waiting for approval from Steam on the initial build.
Here's what to expect from the playtest:
7 different songs of varying levels
roguelike learning system
upgrade system
progressive difficulty system
The game is still in early stages, so there will be a lack of polish in several areas - I'm mainly trying to get feedback on the overall game loop and catch technical issues before the public demo.
I've updated the background style for consistency between levels - they're now more colorful / more abstract! I'm excited to add more backgrounds, which is a lot easier to do with the new style.