Welcome to Organic Builder, a simulation game which teaches chemistry and biology by providing you with an artificial chemistry where you make the rules.
You can do incredibly complex things within the simple constraints of this system, and the last puzzle for you to solve is making a self-replicating cell. Are you up for the challenge? Download the game (jar file)
Here's the explanation of how the game works on their website:
In real chemistry, the bonding rules are written like this 6*(CO2) + 6*(H2O) + light => C6H12O6 + 6*(O2), where carbon dioxide and water (six of each) react (in the presence of light) to form glucose and oxygen. This is the reaction that plants use to photosynthesise.
In an artificial chemistry we use simpler rules, like this one a0 + b0 => a1b2, rather than use the atomic types seen in nature (hydrogen, oxygen, etc.), we use arbitrary letters: 'a', 'b', 'c', 'd', 'e' and 'f'.
And rather than have complicated rules for determining which molecules will react, based on charge, valency and shape, we use the state number (0, 1, 2, ...) to decide if the reactants match. For example, in the reaction above, two atoms a0 and b0 will become bonded, and the 'a' atom will take on state 1 and the 'b' atom state 2. They could each be bonded to different atoms at the time, that doesn't matter. The types of the atoms can't change (like in real chemistry), just their states.
And rather than worry about energy considerations, we assume that if a reaction rule is present then it is energetically favourable. All of these changes leave you with a very simple system but one in which you can still do some very interesting things. If you have come across cellular automata (wikipedia link) then the system will be somewhat familiar.
This thread is intended as a hub for organic builder enthusiasts on TL to exchange strategies and hints.