Since the Dev seems to be so incredibly responsive: Please don't do a mute button. Sliders are so much better in every way. Like any good nerd I have several programs trying to send me sounds at any given time, I like your sound but I don't need it breaking my ears while I'm waiting for a facebook ping and yapping on Vent.
1) The default gun CAN be used through every mission, even on realistic, and yes even level 7. 2) The twitching isn't THAT hard to compensate for. Just wait it, adjust, fire. 3) If you can't handle the default bolt action rifle: Do the tutorial achievements! You can buy any gun you want quickly. 4) Use arcade mode to practice if you need to. 5) If you still fail, vote this down and post yet another "omg game sux" comment.
Score should be based on how many build points you had leftover on each level, not the number of levels you've completed. Some of the levels can be completed with very few blocks and it would add an extra level of challenge for us. I know I'd likely spend far too much time wondering how my friends completed levels in 6 fewer blocks than I could.