10001100-01 Achievement in 140
Complete the first stage
How to unlock 10001100-01
Story-related; cannot be missed.
The first stage is entirely an introductory stage. It may be slow going at certain obstacles, but there are plenty of checkpoints throughout the level. When you get to the boss at the end (where you grab the floating triangle), I highly recommend beating him without jumping on your first playthrough to also unlock "0011010100000000." This avoids the need to replay the first stage.