re = /^(?:Play3|One|Hero12|.*\b(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\d{4}\b.*)$(*SKIP)(*F)|\d+(?:,\d+)*$/m
str = 'Play3
1,715,455
123,777
One
23,000
etet55
Hero12
vrtg1,345
vrtg001,345
2
Jan2003
0000
0001
12345
45,77
45,777
045,777
Jan2003
03,1
0,1
0,000
0,001
'
subst = '\\n$0'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html