Ruby Discord Halloween Challenge.rb

BOARD = {
  nil  => %q[SCARY?!],
  '🎃' => %q[BDEFGH ],
  '👻' => %q[IJKLMN'],
  '🍬' => %q[OPQTUV,],
  '💀' => %q[WXZ.#$:]
}

row = BOARD[nil]
File.foreach 'input.txt', chomp: true do|line|
  line.each_char do|char|
    row = BOARD.fetch(char) do # invoked if key not found
      print row[char.to_i]
      BOARD[nil]
    end
  end
  puts
end

⛳1 -p @UlyssesZh.rb

#!ruby -p
gsub(/(\D?)(\d)/){'SCARY?!🎃BDEFGH 👻IJKLMN\'🍬OPQTUV,💀WXZ.#$:'[/#$1.{#$2}(.)/,1]}
# Well whadday know, @UlyssesZh’s algorithm and `⛳1 bytes[3].rb`’s are the only ones that covers the entire original board.
# Though this one too can squeeze some extra chars by simplfying off the the unused chars:
# ``gsub(/(\D?)(\d)/){"SCARY?!🎃BDEFGH 👻IJKLMN'🍬OPQTUV,💀WXZ."[/#$1.{#$2}(.)/,1]}``

⛳1 -p.rb

#!ruby -p
gsub(/(\D?)(\d)/){"WXZ.IJKLMN'__BDEFGH ____OPQTUV,_SCARY?!_"[$2.hex-($1+?^).ord%77/2]}

⛳1 based on @UlyssesZh’s.rb

puts$<.read.gsub(/(\S??)(\d)/){'SCARY?!🎃BDEFGH 👻IJKLMN\'🍬OPQTUV,💀WXZ.#$:'[/#$1.{#$2}(.)/,1]}
# ``puts$<.read.gsub(/(\S??)(\d)/){"SCARY?!🎃BDEFGH 👻IJKLMN'🍬OPQTUV,💀WXZ."[/#$1.{#$2}(.)/,1]}``

⛳1 bytes[3].rb

puts$<.read.gsub(/(\S??)(\d)/){'BDEFGH OPQTUV,WXZ.#$:SCARY?!IJKLMN\''[$2.hex-($1+?👼).bytes[3]%6*7]}

⛳1.rb

puts$<.read.gsub(/(\S??)(\d)/){"WXZ.IJKLMN'__BDEFGH ____OPQTUV,_SCARY?!_"[$2.hex-($1+?^).ord%77/2]}

⛳2 based on @sampersand’s.rb

puts~/\d/&&"SCARY?!BDEFGH IJKLMN'OPQTUV,"[($`.bytes[3]||0)/3%6*7+$&.hex]while gets
# @sampersand’s originally-shared non-acrostic edition:
# ``print~/\d/?"SCARY?!BDEFGH IJKLMN'OPQTUV,"[($`.bytes[3]||0)/3%6*7+$&.hex]:" "while gets``