Thanks, I'm glad you liked the game!
Thanks for your kind words. I'm working on a sequel for FoE but it's not nearly finished. I encourage you to start working on a similar game, it's fun to play with those mechanics and there is so much to explore. Here is another game you may like to try: https://geckoo1337.itch.io/project-a also there is Antichamber and soon (I hope) Magnifold Garden.
You got me curious so I looked at asset from Unity Store and there is quite some:
There is free ones like https://assetstore.unity.com/packages/tools/particles-effects/gater-portals-system-59185
This one seems really great (but not free) and can play on scale (spoiler for FoE episode 2 ...), and there is a demo only
https://assetstore.unity.com/packages/tools/particles-effects/portalkit-pro-vr-a...
Even if you don't use Unity, it can be great for learning. I saw video of Memory of a Broken Dimension but did not know it was out, I need to try it!
You can find the OST, as well as other tracks, on this page from Legulysse, the creator of the sound track. http://legulysse.free.fr/?page=audio
I will also add the OST to the itch.io page of FoE today.