Daaaaaaamn, that's a lot of work ! Congratulations, that was a really polished and complete game, in only one week, that's impressive ! The art style is really good (3 environments, really ? Wow !), the music fits perfectly well and the sounds are hilariously good ^^ ! The gameplay is enjoyable, the dash is a really nice addition and makes the whole game very smooth =).
For doing such a quality game, you seem to be invested in game making, so let me expand a bit on what, in my opinion, you could improve in your game (and what to check for the next =p). Keep in mind that this is an awesome entry, and these are just some little suggestions for going a step further =).
My first little concern is about the level design. There are a lot of levels, some of them introduce new ennemies, which is really good and makes me want to see more, but some other levels feels more like "fillers". I think I would have enjoyed less levels, but more new mechanics in each level ^^ (and a bit less backtracking).
The balancing of the game is also a little issue. In general, most enemies can be killed just by spamming the bat (even the clown, that you can kill in 3 hits before he releases his attack). Enemy design like the mouth or the key where interesting because they needed to use the dash at a good timing (either as a gap-closer, for the mouth, or a evade tool, for the key). I would have enjoyed a more "beefy" clown that couldn't be one-cycled ^^.
Finally, I can understand why, in a sense, this respects the theme (the whole "it was a dream" thing), but I really enjoy when the theme influences the gameplay, and not only the story/graphics of a game.
Ok, I'm always worried when I leave comments like this, because there is more text for "what can be improve" than for "what is good", so let me repeat myself : these are just little hints for you to become better, but, in its current state, the game is REALLY good. You worked hard and it shows, so congratulations. You can be really proud of what you've done !