The brain structure of the standard Creatures 2 genome does not appear to differ greatly from the Creatures 1 genome. There do appear to have been a lot of additional features added to the brain lobe functionality that could be taken advantage of in future genomes so there is definitely more potential for new brain modifications that could not be done in Creatures 1.
On this page I'm outlining what I've discovered to be the differences between the Creatures 1 and Creatures 2 brains and what new features seem to have been added in Creatures 2.
The brain layout is much the same as in Creatures 1. There is an additional brain lobe (lobe number 9) called the Sandrabellum or Regulator lobe. The lobe details page explains the functionality of the new lobe.
The Stimulus Source lobe has a state variable rule in Creatures 2. It uses new Creatures 2 SVRule opcodes and the effect of this new rule is described in the description of this lobe.
The Drive lobe has been expanded and is now 18 cells in size. Of this the first 17 are used leaving 1 spare. This is to cater for the new drives in Creatures 2 (Injury, Suffocation, Thirst and Stress).
The functionality of the remaining lobes is much the same as Creatures 1. The only differences is that some of them uses new state variable rules but the operation of the lobe is exactly the same as Creatures 1.
Many new features appear to have been added to the potential brain functionality of Creatures 2. The following is what I've been able to find out using Sandra Linkletters D-DNA analyzer, The Creatures 2 Strategy Guide and examination of the advanced science kit in Creatures 2.
There appear to be some new state variable rule opcodes added. The new opcodes (in addition to those described for Creatures 1 in Tutorial Two) and what I think they mean are:
Updated 10/04/1999: A full table of the latest state variable rule information for all creatures versions is now available. The table below may be out of date and you should refer to the svrule page for current information.
| Opcode | Description |
|---|---|
| 32 | The integer number thirty-two. Can be used for calculations. For example, adding or subtracting one from the current state. |
| 128 | The integer number 128. Can be used for calculations. For example, adding or subtracting one from the current state. |
| rnd const | Not yet known. |
| chem4 | Represents the current amount of chemical 4 in the brain lobe. This appears to be a new chemical as Creatures 1 only had chemicals 0-3. |
| chem5 | Represents the current amount of chemical 5 in the brain lobe. This appears to be a new chemical as Creatures 1 only had chemicals 0-3. |
| leak in | Not yet known. |
| leak out | Not yet known. |
| curr src leak in | Not yet known. |
| FALSE | If the previous opcode evaluates to FALSE (ie. zero) then execute the remaining opcodes otherwise the value of state is zero and the SVRule completes. Creatures 1 had a TRUE but no false. |
| multiply | Not yet known. |
| average | Not yet known. |
| move twrds |
This opcode takes two arguments and operates on the value of the previous opcode. It will take the value of the previous opcode and move it towards the
first argument by the value of For example: ' This opcode allows you to perform a fairly complicated calculation while only taking up a few of the SVRule opcode places. |
| random |
This opcode takes two arguments. It returns a random number between the first argument and the second argument. For example: ' |
Note that the above are mostly my interpretation of what they do from reading the C2 strategy guide so take with a grain of salt until more official documentation becomes available.
The size of the rules have been increased from the original of 8 opcodes in Creatures 1 to a size of 12 opcodes in Creatures 2. This means the rules can now be more complicated. This is good as some of the new opcodes operate on multiple arguments and therefore take up more space.
Two completely new state variable rules have been added. These are described in the D-DNA analyser as 'Backward Property Rule' and 'Forward Property Rule'. I don't know how these relate to the the brain at the moment - whether they are dendrite or cell related and what effect they have. Currently the Creatures 2 genome does not use these rules.
Although not directly applicable to the brain model there are new Loci available in Creatures 2 emitters. The values of these Loci can cause chemicals to be emitted using the Emitter gene. The following appear to be some of the interesting new Loci added:
There are others but I haven't looked into them in any great depth.
There are new receptor loci added as well for the new brain chemicals (chem 4 and chem 5) as well as other similar brain related details.