Argh!
https://groupees.com/vip4They had this cool expensive bundle... which accepted Groupees coins!
And no word about it!
And I only noticed this bundle now!
And I can't use coins anymore!
Conclusion: try to avoid trading for these games with real value... I'm pretty sure many buyers used up their existing $15+ coins which they got for free earlier. It's just that I'm not in the mood to trade these days and I missed out on this. (Well, the Star Trek games were right up my alley... Sacrifice as well but I have many of those on GOG already.)