Timberman - "Mighty Mr Tree" Unlock (score of 1126)
For the achievement (and respective character) you need a score of at least 1001 (or to chop 150,000 cumulative wood, but that's way too long of a grind). Took me around an hour straight of playing a bunch to get it.
Also, keep in mind that in the webcam the arrow keys are upside down. So the keys I'm pressing and where I go in-game looks reversed lol