Thank you, so glad you liked it! We also wish there were more songs in the game, but due to the limitation we had on making the game, this was all we had time for.
But there are actually 9 songs in the game and more like 3 different themes. But to make 3 different difficulties for each of the 9 songs would've required like 27 beatmaps, and we simply didn't have the time to do it.
But again, thank you so much for playing and for loving the experience, that's all we really wish for.