This game is incredibly cute, and I love the option of characters by restarting! The speed boost was a great add the concept is easy to follow.
It seems the trash dispenses more as time goes on and the scatter of them and the random speed shells kind of let luck determine the outcome. I played 3 times and got 700 something each time, so there didn't really seem to be a learning curve or room for improvement. I would possibly reduce the percentage of the pollution based on picked up items rather than just increasing it. This should allow for more play time and additional score variation. If there was 1 power up that expanded the range of grabbing momentarily that could be on a recharge timer, it would give the player more control of their playthrough experience as well. As far as a goal goes, it seems it's just to get score so I would add a rank or comment to the score to encourage more playthroughs.
Very nice work- super fun, cute and awesome concept!