For a demo this is good, but could use some work before it reveals it's final form. Firstly, the timer and lap counter overlays the track, which is distracting and takes attention from what should be focused on: the car and racetrack. Also, a graphics/aesthetics revamp could really help this game succeed. Finally, hitting the outside seems a bit too punishing, and will be especially difficult to deal with if other racers are introduced. Maybe a simple slowdown(really, really slow) can make it less brutal on your time, while still preventing cheating. Or maybe some grass near the edges of the track that slows the car down, but some walls in the center that function just like the grass currently does.

While the particles exist, they don't work as I believe you meant them to. The bomb scaling works well, and damage does scale with bomb size. However, the bubbles come off more as an annoyance than a novelty. I think if they were transparent that would make them at least a little less obnoxious. Gameplay-wise, the game played alright, but the sub felt a bit slow and not like a submarine would really feel while controlled underwater. The graphics were okay, but it wouldn't hurt to have them upgraded/updated. Finally, some sound effects and/or music could go a long way in this game.

Although the ball bounced at weird angles sometimes and didn't bounce from some bricks, this game was a good minute or more of fun until my ball got stuck on level 3. Maybe a button to reset the ball could help alleviate this, or a mechanic to reset the ball if it's not moving for too long. Also, the ball handling and reactions with the paddle could be improved, for example if the ball is to the side of the paddle and you move towards it, it will spam the sound and not move again. For another example, sometimes the ball will bounce the opposite direction it should have on some occasions; usually when bouncing off the top. And others have already mentioned this, but the sound where the ball hits the paddle is a bit annoying. Maybe it could be quieted, or some music appended to drown it out. This game is [fun]ctional, but it could be so much better with some bug fixes, improved ball interaction, and some audio/music as well.