I’ve updated the molecular computer demo and I’ve created a new demo page where you can see all chemical reactions needed for building a molecular computer.
If you are interested please read and play with both demos.
The purpose of the demo is simple: if anybody would identify real chemical reactions between small molecules and (invisible in the demo) other molecules, one per move (I call them “moves enzymes”), then it would be possible, in principle, to design molecules which compute, by themselves, without any laboratory management, by these chemical reactions. Any such molecule should be regarded as a program which executes itself. The result of the computation is encoded in the shape of the molecule, not in the number of (more or less arbitrary) chosen molecules.
See also the post Molecular computers.