I liked this game, the concept is interesting enough, and I had fun figuring out the solutions.
In response to TesloStep's comment (SPOILERS if you haven't reached level -1 yet):
1. First, what you want to do on level -1 is, make sure that you have no lives, and that the second digit of your score is 7--e.g. 07, 17, etc. (I'm not sure about the no lives part, but do so just in case)
2. After that, turn the music off, then jump on the enemies. (Again, I'm not sure that you have to turn the music off, but do it just in case) Then use the score tiles to get to the 1-up.
3. If you've done this right, the second digit of your score should now be 4--e.g. 14, 24, etc. Use the score tiles to jump onto the spikes (the second digit should now be 3) and then use the sole 1-up to revive yourself (the second digit should now be 2).
4. The second time the countdown begins, wait for it to count down to 4, and you should get to level -2. Once there, simply ignore the 1-up (I don't know if getting the 1-up counts, but ignore it just in case), drop onto the spikes, wait for the countdown to finish, and you should get a "The Real End" message.
Hope this helps!