100% Space Beret
First, click the ‘One Life’ option in the main menu.
This will unlock the ‘Play one life mode!!!’ achievement.
Move into the yellow marker once the ‘cut-screen’ of text has completed.
Kill one enemy by right clicking (or more, if you wish).
Spam ‘R’. This will, for some reason, restart the mode but triple your score.
This will unlock ‘Got 500 points!’ and ‘Got a 1000 points!’.