Grid Puzzle

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ACROSS

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DOWN

[/box][-]1) Sword Counterpart
4) Not
6) Feng shui principle
9) Candy stix
13) What (hits+bb+hbp)/(ab+bb+hbp+sf) should probably be called
14) 21 on a die
16) PAX and MAGFest, or E3 and C2E2, or SDCC and SXSW
18) Letter-named ski lift
20) Various abbreviation, missing a letter
22) Not them
23) Squib goo
24) Drug cop
26) Prefix for sane
27) Furniture location
29) J Edgar Hoover
30) Before ter-
32) Hydrocyanic acid
33) Protecting
36) LMAO
37) Gatekeeper of Gozer
38) Male spelunker
41) 6 handegg pts.
43) TV's
45) 2019's even Atlantics
46) Additional email recipients
47) More of -y
48) Health alt. in BotW
49) Greek trident?
51) Incomplete combustion product
52) Eggplant cheese's city
54) Short bird's "like" alt
55) A foot belonging to a kitty
57) Chuck Testa
58) Spekkio's final form
59) 135, to final NASA SS flight
62) Knightly title
63) ACT alternative
64) Wildebeest
65) Can you hand me a moist _?
68) __ GOD PLEASE __
69) Uh... everyone loves... cake?
71) Home of GWS Giants
72) Yo!
73) Destructive 2017 hurricane
75) Store where I buy my clothes
78) Wisdom
81) Dica cielcunobiryxoed
83) Does not imply WIS
84) Soprano's solo
85) Not dah
86) G# alt
87) Bagel addition with capers and schmear[|]1) Betting pool
2) Order vs Chaos's final final minute's start
3) Flatbread
4) Not gotten from dQw4w9WgXcQ
5) B3
6) Good luck with this mess
7) Densest moon
8) Nocopi stock
9) Partner with 74d
10) Veeeery coooold
11) Foreigner gas
12) Sanikiluaq
15) One more thing
17) [insert rainbow 'the more you know' .gif here]
19) Lottery
21) Latin shinbone plural
25) Gy to Sv weighting factor representation
28) Follows more or less
31) Look! Bovines!
33) TTwo insttrumentts playing ttogetther
34) That thing nobody reads
35) Religious splits
37) Zetatesla per steradian
39) Pearl chat prefix
40) Egyptian snake
41) BPM source
42) Former official Spanish dict.
44) Relaxation site
47) Type of club
50) PlAveCt
51) Pollux's twin
53) Voids
55) Grad div
56) SethEverman
58) 4e69774c6749
60) Helioptile inspiration, according to Germany?
61) 76d translation
62) Until this point
66) Common evolution suffix
67) How the knot competition finished
70) Rope or wire
71) Simile phrase
74) Partner with 9d
76) Source of wild draw four
77) Arlington a capella group
79) Sports it's in the game
80) If yes accented
82) Sound Unit[/2x2][/box]

Errors I've found in the image are corrected in the text list and colored bright pink. I'd like to thank a52 for the inspiration for this puzzle's theme. The question is: Can you figure out what that theme is? and can you do it?