Android platform game

I’m working on a platform game for Android devices.

I’m not sure what the player should look like ( It will not be a ball as in the video) and if I keep the walls black.

Here’s a video of the project.

Personally, I’d change the colour of the walls. Why? Well, this is my personal opinion, but it just doesn’t fit the aesthetics of many, many apps I am using. And since they look nice, I am learning to like them - you know, magentas, soft greens and everything.
About the player, I’m not really sure. I’m not really sure how important this choice might be, but from the pragmatic usability point of view, it has to be something easily distinguishable (always, at all points of the game) from the background, so the user won’t be losing because of a technical failure.

good luck with your development!