Zendo, play by forum

[Simon]

CHA
CH
C
CA
ACHRLES
ACEHRLS

-- Simon

[Proxima]

White:
ABEGILR
ACEHLRS
ACEHRLS
CABREL
CH
CHA
GAB
GABRIEL

Black:
ACHRLES
C
CA
CHAR
CHARLES

[Proxima]

At Simon's suggestion, I compiled a list of all the rules that have been used in the game so far

All rules take the form: "A koan has the Buddha-nature if and if only..."

For rules that refer to vowels/consonants, it is noted whether Y counts as a vowel for this particular rule (although in three cases, the round ended without resolving this ambiguity!)

1. (Simon): its letters are not all different
2 (Insane Steve): at least half its letters are vowels (Y is consonant)
3 (geoo): all letters have either mirror or rotational symmetry
4 (ccexplore): it contains an odd number of consonants (Y not tested)
5 (möbius): exactly half its letters are vowels (Y not tested)
6 (Minim): each consonant occurs at most once (Y not tested)
7 (Simon): its first letter is alphabetically earlier than all its other letters
8 (Proxima): its length is greater than or equal to alphabetic position of its first letter
9 (ccexplore): it contains at least one letter from "AKHTBN" and letters from that string occur only in that order
10 (Clam): it contains two letters that are consecutive in the alphabet
11 (Nepster): exactly half its letters are from the first half of the alphabet
12 (Proxima): its first and last letters are the same or their alphabetic positions differ by a multiple of 4
13 (Ramon): it contains the letter whose alphabetic position equals its length
14 (Nepster): when arranged alphabetically, its last letter is a vowel (Y is consonant)
15 (Minim): the sum of alphabetic positions of its letters is prime
16 (Proxima): its length is square or triangular, but not both
17 (Clam): its third letter is the same as its third letter when arranged alphabetically
18 (namida): it has at least three letters, and at least half its letters have (alphabetic position - 1) a multiple of the length, with the first letter counting twice if it is a multiple
19 (Proxima): for each n, the nth vowel either does not appear or appears n times (Y is vowel)
20 (namida): every pair of adjacent letters are either the same or from opposite halves of the alphabet
21 (Proxima): it contains an odd number of letters with exactly one vertical line segment
22 (Simon): its first letter is the same as or alphabetically earlier than all its other letters

[Simon]

<SimonN> oh my, I hosted only 3 rounds, and used the same rule for 2 of them
<Proxima>
<SimonN> and the other round was the very first round with the easiest rule imaginable

ACE
ACH
XAXXIEX
XXAXXEX

[Proxima]

White:
ABEGILR
ACE
ACEHLRS
ACEHRLS
ACH
CABREL
CH
CHA
GAB
GABRIEL
XAXXIEX

Black:
ACHRLES
C
CA
CHAR
CHARLES
XXAXXEX

[Simon]

A
XA
XXA
XXXA
E
XE
XXE

[Proxima]

White:
ABEGILR
ACE
ACEHLRS
ACEHRLS
ACH
CABREL
CH
CHA
GAB
GABRIEL
XAXXIEX
XXA
XXE
XXXA
XXXE

Black:
A
ACHRLES
C
CA
CHAR
CHARLES
E
XA
XE
XXAXXEX

[Simon]

OMU
UTO
RR
HC
UOIEA
AC

[Proxima]

White Koans
ABEGILR    CABREL     HC         XAXXIEX   
ACE        CH         OMU        XXA       
ACEHLRS    CHA        RR         XXE       
ACEHRLS    GAB        UOIEA      XXXA       
ACH        GABRIEL    UTO        XXXE       

Black Koans
A          CA         E          XXAXXEX   
ACHRLES    CHAR       XA         AC         
C          CHARLES    XE                   

[namida]

RLIGEBA
SRLHECA

[Proxima]

^ both white

[Clam]

G
H
R
S
GG
HH
RR
SS

[Proxima]

White Koans
ABEGILR    CHA        RLIGEBA    XXE       
ACE        GAB        RR         XXXA       
ACEHLRS    GABRIEL    SRLHECA    XXXE       
ACEHRLS    GG         UOIEA      SS         
ACH        HC         UTO                   
CABREL     HH         XAXXIEX               
CH         OMU        XXA                   

Black Koans
A          CA         G          XA         
AC         CHAR       H          XE         
ACHRLES    CHARLES    R          XXAXXEX   
C          E          S                     

[namida]

I
O
U
Y
KING
QUEEN
JACK
JOKER

[Proxima]

White Koans
ABEGILR    CHA        OMU        UTO       
ACE        GAB        QUEEN      XAXXIEX   
ACEHLRS    GABRIEL    RLIGEBA    XXA       
ACEHRLS    GG         RR         XXE       
ACH        HC         SRLHECA    XXXA       
CABREL     HH         SS         XXXE       
CH         JOKER      UOIEA                 

Black Koans
A          CHARLES    KING       XE         
AC         E          O          XXAXXEX   
ACHRLES    G          R          Y         
C          H          S                     
CA         I          U                     
CHAR       JACK       XA