Version 4.1
I had time to do a full play through recently which lead me to update to version 4.1. It took me just over 10 hours to do everything there is to do.
I added a few more puzzles, made a few things easier and a few things harder. I found several bugs which are now corrected.
If you see a version on the title screen of the game earlier than 4.1 you can transfer your save files (named Save1-4.rvdata in the game directory) to the new version by dragging and dropping them into the newly downloaded directory.