This YouTube video by Eurydace Gaming will guide you on how to locate the 9 broken CD parts to unlock TOTC:

Once you unlock TOTC, Simple start a game, hold the Down arrow, and press X decently fast. No need to press X as fast as you can, but aim for around 6-10 times a second. Press left and right while still holding down to move around. the dashing will make you invincible, and holding down will allow you to dash without a cool down, and pass through the brutes without bouncing off, if you do not hold Down there is a small cool down before you can dash again, and you will bounce off them, and possibly take a hit from nearby enemies.

Press and hold up arrow to launch into the air and collect the arrows that are near the top.

If you collect a full bar of arrows, any further arrows you collect will give 500 points which will speed up the process a lot. if you are in trouble you can hit Space to start nunageddon and kill everything on screen.

Once again, just HOLD down arrow, and TAP X fast. That's all you need to do to score 15K

Enjoy your basically free achievement. Get the world record high score with this if you wish.