I'm trying to collate the special rules of each army in the game, and graph them. The idea is to see which armies occupy a similar space (rules-wise), which are more distinct, and how well those distinctions have been made.
The method - each unit, and each special rule, represents a node. Where a unit has a special rule, that unit's node and the special rule node are connected. Similarly, special rules that confer other special rules are connected (so a Kabalite is connected to Power from Pain, which is in turn connected to Feel no Pain, Fearless, etc). I have taken only special rules in a unit profile, not special rules that are accessed through wargear or other upgrades. I haven't considered weapons yet - that will be a separate graph I think.
Here's what I have so far. The size of each node represents the number of connections. So you can see that Deep Strike is well represented.
The Dark Eldar are in purple, and unsurprisingly hang around the Night Vision and Power from Pain nodes. There is some interaction with other rules, Fleet and Feel No Pain in particular.
Chaos Space Marines are in maroon. Notably they have a lot more nodes, as there is a lot more to choose from in their codex. But most of these have fewer special rules, so are less connected.
Chaos Daemons are in bilious green. They collect around Deep Strike and Daemonic Instability, but otherwise are quite separate from the other two armies, particularly since a lot of their rules are through army specific intermediate rules - the have access to Fleet and Rending mainly via Daemon of Slaanesh, for example.
Here I have run into a problem however - I don't have any more up to date codicies (except necrons, but since they are due to be redone in a month or three there doesn't seem much point)! So I will need to slowly go around the other books next time I catch up with my gaming group. In the meantime, if you wanted to see one of your other armies represented, please feel free to give me a list of units and their special rules
(no points values, please
)