At the time of my comments, the description only stated

May not work

without further explanation. And I found it funny for several reasons:

1. "May not" can be interpreted in different ways. One of which is "prohibited to" or "not allowed to".
2. In terms of stating something one is unsure of, "may not" is used to describe a probable outcome while "might not" is used to describe an unlikely outcome.
3. Since it's an unrestricted level 0 giveaway and runs for 5 days, it will most likely crack the 10000 entries mark.

So all in all, it was asking for a 50P "investment" for an estimated ~0.01% chance of winning a key that either "is not allowed to work" or "probably won't work". Sounds funny to me. ^^

Giving away some old not-sure-if-it-still-works key for some old game that has been bundled a thousand times or has been given away on IndieGala or something similar is not quite the same as giving away one of the most popular unbundled (and probably never to be bundled) games that barely went under the 30€ mark in keyshops and didn't yet crack the 35€ mark in official shops.

And to be honest, the addendum "as it came from G2A" doesn't really make it better in my eyes. Just a little bit less funny. And for the record: I am not assuming they necessarily act in bad faith. I just don't think it's a good idea to do a giveaway like that nor is it to enter under these conditions. But to each their own. ;)