Hi! thank you so much for the in depth review! sorry for the unituitive mechanics. For the windup, the acceleration should be instant, but it might be a bug. You're right about the dash buffering, but unfortunately, we didn't have much time to tweak the timing of the dash.
The cards upgrade your cards, and equipping those will give you bonus effects. When you open your inventory, you should see your unlocked cards with their rarity, which starts at "RUINED." picking up a card will add one to that cards count, and collecting enough will upgrade your effect (e.g. the muscle card gives you +1 damage but collecting three blue cards dropped by the goblins will give you +2 instead).
The gold capsules are collectable items, which can be traded in to an NPC for bonus money/a new card.
For the boss, I think I know what you're talking about. The boss (if it was the first one you faced) has an attack when reaching a low amount of health where it will slam into the ground. You can dodge it if you look at its mouth and dash when it turns red (requires good reaction time, but we probably should've added more telegraphing). Defeating that boss will drop a weapon that lets you explore the second area.
For the neon signs, we wanted to add those but didn't have time (we also wanted to add lots of other things to the environment to help guide the player)
Again thank you for the long review!