This is a solid puzzle-platformer. I love the idea of the portal and I like how you created different mechanics to take advantage of it. The look of the portal and the effect of going through it are well done.
There were a few times I found myself teleporting the player or other objects by accident. Also, sometimes, when the next level would load, I would immediately warp something unintentionally because my cursor happened to be in the wrong place when the new level began. I think one potential work-around to this could be by having the portal disabled at first until you click the mouse button. At that point, you could toggle the portal on and off to prevent accidental warps.
Two of the levels, the one with all the flying things that block your movement, and the one filled with tons of yellow cubes, were a bit too chaotic and didn’t seem to fit the design of the rest of the levels. Unless I’m missing some intended strategy, I ended up just rushing through with the character and winning by dumb luck. Other levels allow the player to take a step back and think about how you want to arrange things with the portal, but these two levels seem to contradict that design.
I think this is a great concept and an interesting interpretation of the theme. With a decent variety of mechanics already, I think you could easily expand on this idea with even more levels and mechanics. Thanks for submitting!