First, we needed a list of the items to collect. That's why I decided to make the list large on the screen, so the player could easily read it and clearly see what they've already collected. The same issue applied to the timer, which indicates how close the player is to the end of the game. The hardest part was making the feedback when interacting with other customers both pleasant and understandable.

For the boost we spent too much time choosing the correct shape. We also added the boost input to the UI to make it easier for the player to use.

As for the visual design, it was challenging. I went through many iterations, but I eventually ran out of time. In the end, I decided to go with the theme of an elderly person doing their shopping. I chose a paper theme for the list and other interface elements, and used a watch instead of a smartphone for the stopwatch. I also tried to make the rewards look like credit cards, so the player would feel like they were taking someone else's card and saving time while shopping.