I really enjoyed the concept! Racing snails and the plane mode had me grinning from ear to ear, and I liked how the big snail destroyed the environment as it rolled through! Kudos for a wonderfully whimsical idea and presentation. The game is quite difficult, and I feel that having some power up or item that temporarily boosted your speed would add a lot of depth. That way, you could afford to slow down slightly if you hit a blade of grass and not immediately die. It would also add depth in that you'd be actively trying to reach it instead of just avoiding obstacles, playing into the idea of risk/reward. That said, your first game jam game was much better than my first, and you should be very proud of how this came out :)

If you add a leaderboard for the death counter, I will be in first place. This counter has reached a value in a very short time that I can never reach with the score counter in my whole life. The game is cute but it could benefit from making it easier first (less obstacles, lower evil snail speed, etc) then ramping up the difficulty as time goes on. To reward hardcore players, you could add stars or coins in some locations that increase the score so that newbies can ignore them and focus on surviving while hardcore players would seek to both collect the coins and outrun the evil snail. Overall, good work.