This happened on a repeat playthrough (trying to get all the collectables). Early in the game there is a box that has a magnet and a strange lock piece in it. I took the magnet first, and then was clicking around avoiding the lock piece checking to see if there was anything else in the box. Something I did closed the box and it was removed from both the scene and my inventory, leaving me with no way to get the lock piece required to continue....

Hi. On a hospital gate location I combined stick with a band and instead of getting slingshot both elements disappeared and I'm left with nothing. Reloading the game doesn't fix this and I'm stuck on a level. I was enyoing the play but I don't think I want to waste time and replay the game again when I don't know if such thing will reproduce again....

I have the piece of paper with coloured squares on it but I don't know what I'm supposed to do with it to get a 3 digit code.

So?

Did one HO without even one mistake, but it did not unlock. - I've started a new game and tried on the first HO in the game and got it now. Strange.