JMich: They could have added it as Free Wallet (old Store Credit), which means it would have an expiration date of 1 year. That would cover most of the differences, since they are giving us "real money" when we do a specific task (buy a game that costs more than the US price). A good accountant/lawyer could argue that "Having an account on GOG registered before August 29, 2016" counts as a specific task.
Which would still require terms of conditions to be drawn up specifically for this one promotion, because the existing terms covering store credit clearly only apply to the case of games being bought. And I suspect on the accounting side it would still have to count as a bottom line-reducing liability even if there's a time limit in place.
IAmSinistar: Okay, once again, the problem is in symbolically viewing GOG Wallet funds as analogous with cash. They are only so if I can withdraw GOG Wallet funds and convert them back into cash. If I cannot, then they are no different then me buying a handful of tokens at an old coin-op arcade.
Sigh. There's no difference
to you as a customer. I'm suggesting that there
are very real differences to GOG as a corporate entity, and they're very much non-trivial. If you're unable to grasp that distinction even now, I really don't know what to say anymore.
Edit: Incidentally, your coin-op example only serves to muddy the waters, because that's exactly the type of scenario I was talking about where the customers have to actively involve themselves in receiving the "virtual cash". It doesn't just materialize out of thin air as in the unworkable feel-good promo you were suggesting.