At first it's not very clear how the game works. I think you're supposed to rotate the triangles (mirrors) to change the direction of the moving triangle. However all of sudden the spawner stopped firing triangles (I think it was in the third level). I would recommend replacing the triangles that the player can rotate with mirrors to make it more obvious what their function is.
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Thanks for the reply! I was sure that I fixed those bugs before uploading; guess I was wrong, then. I tough that the shape of the Reflectors (triangles/mirrors) was enough to indicate the player what their function was; also I made sure to put instructions on the title screen and the download page so they know what they're going to do; guess that didn't work either.