The game has very nice graphics, and good sound. I like the idea of the portal, it is interesting. But here are some constructive criticisms:
-Already in the first portal it becomes very difficult to pass the game. It cost me 100 lives to go to the next level and, on top of that, losing generates more anxiety to pass it, which makes you make more mistakes. Perhaps to lower the difficulty a little, I would put checkpoints within the level because I happened to die several times near the end and it made me angry to have to start from scratch from that level. I make this opinion on the basis that today's society wants everything now. Few people stop to keep trying to win it, many get tired and take it out.
-There is something in the jump that does not convince me at all. I would try to play a little with the gravity or the mass of the player to see if that way it improves.
-If you have in mind to sell it in the future, I would add the option to mute the music, because although the music is very good and I mean it, after a while of losing several times the music begins to sound irritating.
-A pause menu would also be good, it is not totally necessary but it always adds up.
Out of all the criticism that I comment, I see a game with potential for them to continue developing and improving. By the way I liked the AI of the enemies. I am also currently developing my first platform video game and the part of developing the AI of the enemies seems the most complicated to me, they did an excellent job with that. I hope the reviews help you to improve it. And to move on, developing video games is awesome.
Sorry for the length of the message.