I don't think I will use this. but you know, I can.(WE can!)
Portal. Some mechanics there are hard to be done in Construct. I will just put a list of these mechanics.
1. Momentum. Say, we have 2 portals that can teleport to each other. The player, when going somewhere or falling will have some momentum. How can we save that momentum when going into another portal? The use of physics here makes me go
2. Looking into portals. If you look at a portal, you will see what is going on the other side of the portal. Is there any way to use cameras that show their surroundings in a window?
3. The teleporting itself. The teleporting by itself is not a giant problem(SET POSITION TO XX DUH DUH Y BLAH), but combined with momentum and camera problems it will require lots of thinking, if not updating the whole Construct 2.
Just google if you don't know what Portal is, it's a video game