Hi. It's the second game I play in the game jam. And I really liked it. Here's my opinion. (Also I'm sorry if my english is not perfect, I'm french)
Goods:
-The graphics, the music, and generally the whole artistic direction is very good. Everything together create a really good ambience and a unique world. You put a lot of effort in it and the result is very good. I especially liked the whole visual feedbacks on the snake when you move, it's really well done.
-The concept itself is really good. The two-world puzzle thing is maybe not new but the general ambience and the fact that you have only a few portals and you have to go back to your tail is a good addition to this. (+ the other things like the blocks you push etc)
-The level design is really good. There is a lot of levels and every one is unique. It may be hard to make puzzle game and find good ideas of levels but you succeed to renew and add new mechanics really well.
Things to change (in my opinion obviously):
-I had the impression the snake was a little bit slow sometimes (like it was a little laggy). Maybe you should speed it up because sometimes I "mashed" a direction and 1/2 input was not taken. Especially for the longs last levels where you sometimes have long distance to travel.
-A little thing : on the sprite of the angle tail, there are a few red pixels (nothing extraordinary).
Generally:
A really good game with a cool concept and a lot of levels which renew themselves very well. Maybe just a few little corrections could be made but nothing important.