Thanks for the detailed feedback 😁 yeah it's definitely a shame that i couldn't make time to add all the fun roguelike mechanics I wanted, but it's great to hear that the core loop works well without the additions.
The colours you choose from are your "hand" that are drawn from a "bag" - the core of the roguelike deck builder is hiding in there! In the future, you'll buy new bubbles and items that play with hand size, add temporary bubbles to your hand, add special effects to the bubbles, etc!