I have a semi-functional Portal-alike working but I have no idea on how to stop portals spawning too far into walls causing the player to get stuck and even clip directly through them. I think it's directly related to animation hot-spots and action points or some jazz. Actually, I'm pretty sure of it but a second opinion is always nice to have so I'm tossing it up for anyone to have a look at since I'd have a far easier time showing what I did rather than explaining. I was going to unveil it as a surprise project but noone likes surprises that don't work so it put an end to that plan. Buttons one and two fire different coloured portals and there's platform controls but no jumping and I haven't set up more than four directions so you can only fire portals in those directions. You might not want to fire a portal into another portal since it causes you to get stuck.
Hilariously, you can set up portals so that you fall into one and infinitely pop out the other if they are the correct distance apart and you keep walking in one direction. Just like in the game!