This game is a lot of fun. As a fan of portal 1 & 2, I love the concept. An endless runner where you have to spawn portals in order to not die. I think what I love most is the fact that in Portal, you have to be methodical with your portals in order to solve puzzles. In this game however, I am spamming portals with urgency in order to stay alive. It's the same mechanic implemented in an entirely new way. I think that's really cool. Good work!
I didn't run into any bugs with the portals they most worked as intended. I am playing on mousepad so I kind of wish there was an alternate control scheme other than using left and right click. That's a minor complaint though. Once this game is on Steam, Xbox, and Playstation and has full controller support that won't be an issue.
I wasn't confused by any of the concepts but I also played the portal games so I went in with that knowledge. I think even if I hadn't I would've been able to pick up on it.
That being said, If you made the level start out slower I think it would give the player more time to learn. I feel like there's not a whole lot of time to catch your breath when the game starts.
I would say to add visual elements to your level, but I think that might be kind of distracting. I actually like the plain gray level because it keeps the focus where it should be and its easy to see your portals.
This game is a lot of fun. Good work!