I'll be honest here. It's pretty late, and I was supposed to finish jamming a while ago, but then I thought "just one more". I was not in a headspace to play a puzzle game, so I was pretty glad, that yours was pretty forgiving. Of course forgiveness went out of the window, when at the end the game goes "you could've saved at least this many more". We'll... I guess that's some points for encouraging replayability :)
This is also a nice play on the theme. You can't save them all, but you are encouraged to do better. For a game with graphics this dark, it's an optimistic message.
The game looks and sounds nice. The art has a nice style (reminded me of Limbo a bit), and the sounds the squares make were appropriately cute.
As for the gameplay. I liked the "forgiving puzzle game" thing. It would be nice if more games did this- to pass the puzzle you have to be this good, but feel free to look for the perfect solution if you feel like it. The thing I liked less was platforming. This was not a big deal- the game didn't require too much precision, but the jump was a bit too fast for me. I'd go with slower falling speed, with more control. It would make the parts where you nudge the boxes that are bit higher than you easier.
Over all- I enjoyed this a lot, and it's pretty likely I'll try to beat my score!