This is quite a large demo, there's quite alot of puzzles and it can be time consuming to complete. For those who don't want to do all the puzzles, and just rush through and check out the other areas and even fight the boss (something that I've added for dev purposes) press ctrl-j, that will put you in first person camera mode, press space bar to exit this mode. You'll be able to exit the level bounds etc in this mode. You can use it to bypass the doors blocking access to other areas, doors that would normally be removed after completing puzzles. Just go through the door, to the part of the level where the next area would usually load and press space bar.