Added way more levels (and mechanics exclusive to those levels), roughly doubling the length of the game. These can be accessed the same place the ending was originally.
A few tweaks to existing levels
Completely different ending
Added more music (including one more piece in the existing levels)
Some graphical changes: better title screen, trees in the background, boxes now have a checkerboard pattern, border in full-screen mode, snails rotate now, level transitions look different, there's now a way-less-subtle animation when a snail tries to jump but can't
There's now a bit of coyote time
You can now reset a snail's position by walking past where they originally were
Fixed a bug where a snail would behave weirdly if you were standing on them when activating them
changed/added/removed some text, mostly in the second half of the game
added a "Somewhat simple graphics" option, that only disables the effects that I know are an issue
fixed some issues that were causing the game not to work on some older browsers (now works on Firefox 3, though at least on the computer I tested on doesn't have a good framerate)
hopefully fix a bug where the snail sound repeatedly played (I couldn't reproduce it; I think it's when you die and activate a snail on the same frame, in which case it's frame-perfect)