Wow, thank you for the long and detailed feedback!
1) I'm glad you liked the sound design. I think this is one of my weakest points (along with game design) so it feels nice being validated :)
2) I'm actually quite proud of the art direction so I'm happy to know you liked it!
3) I completely agree with you about the theme (or lack thereof). The original idea was to have a simulation of your future life with the pet, and you could rewind at any time to see different paths. This was already at the limit of fitting the theme as I was worried it would be seen as a glorified "New game" option. In any case, several constraints (time and art, mostly) led to a deviation from this idea to the game we finally ended up making. Basically I liked the idea too much to scrap 2 or 3 days of work just because it didn't fit the theme very well :)
In the end, I justify the rewind mechanic as an abstract representation of training a puppy, as sometimes you need to "go back to basics" in order to teach him well.
In any case, I'm glad you enjoyed the game and thank you for playing!