For the hostile arena 10k part: switch your primary to semi, make one headshot, and let yourself die. You'll have one kill with 100% accuracy, which will give you a final score of 10100 :)
Make sure that you select to start a new game (instead of choosing load game on an empty slot) at the beginning. I chose load first and was unable to unlock achievements. Tried reloading, refreshing, etc, nothing worked. Maybe this is a bug?
Good game, but a little bit more editing on the music would go a long way. For example, Cheetamen II Glitch mix... fine song, but every time it tries to do a sharp loud note, it results in a really annoying clicking/popping noise. There were a few other songs I noticed this on, but Cheetamen II Glitch was especially heinous. Sounds to me like the signal's clipping or something... might want to check the audio file and make sure the wafeform isn't getting maxed out on the sharp, loud parts.
Sierra 7
Tealy & Orangey
Flight
DJManiax