Well, I wrote a Python script that does that. It is not in an elegant state, but it worked for me.

If you have not found a solution that satisfied you and you're willing to install Python in your computer, yet let me know and I'll see if I can upload it to github with instructions.

My inefficient way based on python script tha looks for gogData variable:
1) on chrome open url:
view-source : https : // www.gog. com/en/account
(fix this url first. This forum doesn't allow me to paste urls)
2) copy&paste source code on text file
3) Save as gog.html
4) run the script below

It works today. If gog page changes... who knows.

Notes:
step 1 = browse game list & use "view source"
"save page as" don't work for me. That way "var gogData" is almost empty.

-- python script --

import re

file = "gog.html"

pattern_line_gogData = '.+var gogData'
pattern_titles = re.compile('title"\:"([^"]+)')

for i, line in enumerate(open(file, 'r', encoding='utf-8')):
<space><space>if re.match(pattern_line_gogData, line):
<space><space><space><space>for match in re.finditer(pattern_titles, line):
<space><space><space><space><space><space>print('%s' % match.group(1))

Note: replace <space> by spaces. Don't know how to indent in this editor

Bring up the console host on this page: https:// www.gog.com/en/account


copy and paste the following

var len = gogData.accountProducts.length;
for(var i = 0; i < len; i++){
console.log(gogData.accountProducts[i].title);
}

hit enter, should give you a list, will have to run it on each page of games you owned (if you have more than 1 page worth)