like any minetest mod just install the mod as "automata" in your mods folder
2 Node types, 1 Tool, 1 Chat command
Nothing, optionally depends on WorldEdit in order to use chat command "//owncells ( see https://github.com/Uberi/Minetest-WorldEdit )
This mod provides a "Programmable" Cellular Automata block (Inactive Cell) which you place, then you select the Remote Control tool and punch it to bring up the activation form. Once activated, Inactive Cells become Active Cells and start growing according to the rules you've set. Active Cells turn into Inactive Cells when dug.
"Using" the Remote will bring up a form, this form can be left blank to default to Conway's Game of Life rules. Otherwise custom rules can be entered in "code" in the survival/birth format, for example, conway cells are 8 neighbors, rule 23/3 which means if there are 3 neighbors an empty cell turns on, and already-active cells stay on if they have two or three neighbors, otherwise they turn off. (there are many online collections of Game of Life entities: http://www.argentum.freeserve.co.uk/lex.htm )
Remember that zero is a valid option (for survival at least, not birth -- in this version it is ignored) so that single nodes will grow with rules like n=4, 01234/14. The rest of the form fields also have defaults, but if set allow you to control the direction of growth, the plane that the automata operate in, the trail of dead cells they leave behind (can be set to "air"), etc.
1D automata follow the NKS "rules" as per: http://www.wolframscience.com/nksonline/page-53 . They also require an additional parameter for the calculation axis, obviously the growth axis and calculation axis can't be the same. 2D automata only need the growth axis set, even if growth is set to zero, because the calculation plane is implied by the growth axis (perpendicular to it). 3D automata actually have less options since their growth and calculation directions are all axis. For automata to grow properly, their trail should either be set to air, or they need to be set to "destructive" so that any trail they leave doesn't impede their natural growth in a later iteration.
The remote now has a "Manage" tab which allows you to see your own patterns and pause or resume them. Exporting from that tab is soon to come.
When you hit "Activate" all inactive cells you have placed will start growing (this option will be missing if no inactive cells have been placed).
When you hit "Single" a single cell will be placed at your current location and the rules you have filled out will be applied. This means the cell will die unless it has a zero in the survival rules: 0xx/xxx eg, 01234/14
Alternatively you can select a Game of Life pattern from the right-hand list. Double clicking will give a description. Some of these patterns are extremely large and are actually more like huge machines made of smaller patterns set in precise relation to eachother. Clicking "Import" will create the selected pattern, with the selected rules, relative to your current location. (Most of these patterns are intended for standard Conway 23/3 rules but some are intended for variations on these rules. If that is the case the alternate rules, or any you have entered, will be used -- .LIF collection by Al Hensel http://www.ibiblio.org/lifepatterns/lifebc.zip )
If worldedit is installed, this mod adds a chat command, "//owncells" which allows capturing abandoned automata blocks (active or inactive, abandoned by player or game quit/crash) as well as capturing blocks created by worldedit (which until now have not been useful). This means that by marking a worldedit region, using "//replace stone automata:inactive" or "//mix air automata:inactive", etc, following up with "//owncells" will add these blocks to your "inactive blocks" so that you can activate them with the remote control. You can also mark a reqion around an aborted set of active blocks, or inactive blocks, and as long as they are not owned by a player still in the game (which they won't be if the game was quit and restarted) they also will be added to your inactive blocks to be activated by remote. (note: digging individual blocks does not respect ownership in any way, and manually digging an active block will remove it from whatever pattern it is part of as long as the pattern isn't already past that block in a current grow cycle, as will an inactive block that is dug be removed from any other player's inactive blocks.)
other efficiency improvements to make calculations go faster
non-totalistic rules for 2D and 3D where exact combinations of neighbors can be specified (ambitious)
For other known issues and planned improvements see: https://github.com/bobombolo/automata/issues
Author: bobomb, License: WTFPL
1D Automata (uses NKS rules 0-255) (using RAINBOW mode)