This game isn't long, from our experience playing it, but it is quite fun and mind puzzling. Of course you have played Portal and Portal 2, and so we thought you would like to play this.
Game Link: http://gamejolt.com/games/inverto/15313
There are only 9 stages from here, and we don't know if there is a sequel or not, because it seems to be a game with no story other then puzzle solving.
Thank you for reading and hopefully you'll check it out later
~Azurite and Marcia