The simple joy of throwing around a bunch of objects in a 3D space! Fun stuff. I enjoyed just messing around with the physics for a while. It actually took me quite a bit of time to find the key the first time around.
I did have trouble triggering the "key + good door" ending, but I got the other three. Management probably wouldn't be happy about me standing around in the back room for five minutes, but they also wouldn't love to see what a mess I left for them in those other endings either...