Twisted word-search

Question

This is a somehow twisted word-search.

Every word/phrase should conform to two rules. Your job is to find out the two rules/patterns every word/phrase follows and, of course, to find the words/phrases themselves.

The two rules are mandatory for each and every word/phrase to be considered valid. If either one of the rules is broken, the word/phrase is not valid.

CSV:

S,R,A,G,O,G,R,A,I,L,I  
Y,D,I,R,T,C,I,P,T,G,N
F,D,L,E,P,R,E,H,C,S,K
T,R,Y,G,Y,R,C,Y,U,S,I
E,O,P,E,S,T,O,R,B,E,B
A,Y,W,O,M,E,C,K,E,R,U
I,A,L,R,E,H,A,G,N,B,S
V,L,P,D,S,C,D,R,A,O,B
I,A,G,E,S,A,G,A,M,E,S
S,U,E,L,Z,Z,U,B,E,I,M
E,G,N,A,V,I,P,R,G,V,O
M,Y,I,L,I,R,C,A,L,D,E
B,S,G,M,A,T,I,R,K,O,D
O,L,C,C,I,T,G,D,U,S,U
N,U,S,O,P,P,O,S,B,E,C
G,E,S,C,R,Y,L,N,O,I,T

TSV:

S   R   A   G   O   G   R   A   I   L   I
Y   D   I   R   T   C   I   P   T   G   N
F   D   L   E   P   R   E   H   C   S   K
T   R   Y   G   Y   R   C   Y   U   S   I
E   O   P   E   S   T   O   R   B   E   B
A   Y   W   O   M   E   C   K   E   R   U
I   A   L   R   E   H   A   G   N   B   S
V   L   P   D   S   C   D   R   A   O   B
I   A   G   E   S   A   G   A   M   E   S
S   U   E   L   Z   Z   U   B   E   I   M
E   G   N   A   V   I   P   R   G   V   O
M   Y   I   L   I   R   C   A   L   D   E
B   S   G   M   A   T   I   R   K   O   D
O   L   C   C   I   T   G   D   U   S   U
N   U   S   O   P   P   O   S   B   E   C
G   E   S   C   R   Y   L   N   O   I   T

Hints:

1. Grail (found in the top row) is not one of the words as it does not follow any of the rules. Even though it could be possibly made to follow one of the rules, there is no way it could be made to follow the other rule.

2. There is a reason the word-search is called twisted.

Answer 1

The two rules are:

1. Each word/phrase twists into a rectangular loop, possibly with some letters inside.
2. Each word/phrase is a tag at Puzzling StackExchange :-)

Here is what I've found so far (20 words total, so that should be it)

riddle, cipher, cryptography, tiling, rubik's cube, poetry, wordplay, board games, enigmatic puzzle, logical deduction, visual, geometry, trivia, language, sudoku, movies, cryptic clues, checkerboard, algebra, symbols

It is also possible to relax rule 1 slightly:

If we say that the word needs to have some twists in it, but not necessarily form a full rectangle, we get more words: rebus, liars, game, story, chess, ...

Answer 2

The last one is

symbol (seems that the s is missing...)