Thanks for a long feedback and glad you enjoyed the game! Pulling left and right does something, they apply _very_ little force. I mean bare minimum force to make meteor move. But main part of gaining velocity comes from slingshots as they multiply your thrust a lot.
Second paragraph made my day :) Iterated very heavily on the movement mechanics as it was the catchy part of the game, getting positive feedback put a smile on my face again! I was planing to work on this project, and yes I'm going to add more mechanics to that swings. It needs a bit more polishing, I should probably zoom out the as speed increases so player can see what's coming and take action against objects etc etc. You are definitely right I should inform the player about it's actions, size should be reported as something like health bar etc etc.