Thank you for playing!
I seem to just have forgotten to add in the line of code that places the re/undo function after the giraffe. Have added it back in now, thank you.
And yes, have thought about adding an 'undo' feature even while building the skeleton. It will be possible, though coding wise will be quite fiddly. If I add it in at all I'd want it to allow the player to undo each bone placement in turn, so will have to save them in order, where to put them back to, etc etc.
I do want the game to encourage people to make weird skeletons, and wonder if an undo button would encourage people to make it correctly and take it 'too' seriously. Though another comment said they made a weird one by accident while trying to assemble it correctly, which I realise must be annoying also!