Play Halo 3 for free on PC (just played in a full lobby)

Schrödinger's cat

Yeah, encouraging someone to pirate a game is definitely not allowed. Is like the difference between talking and arguing about something illegal and telling somebody to go do that thing that's illegal. I don't know how it works in other places but over here that can be considered a crime in some cases.
Imagine the following case (a bit extreme but it serves as an example): you are free to question why murder is a crime and even argue that it shouldn't be considered as such, it's immoral but not illegal. But you can't encourage a guy to murder somebody, that's a crime, people are condemned to prision for that.

for starters because the game was never completed and released; for another, because it can still be developed further (repurposed), and so it hasn't yet reached the abandonware stage

I could be wrong and would appreciate correction if so but from what I recall reading many years ago when I worked in the industry it went something like this:
To be classified as abandonware a software product must meet certain criteria:
1) The developer AND the production team must publically state that they are officially abandoning the project and give permission for others to carry on development. Costs are usually not involved.
2) If they have not stated as such and a period of 5 or more years has passed a new developer may ask to continue the work - be it for commercial or GNU use. If given permission, it may then be passed on as abandonware. Costs may be involved.
3) If there commercial and intellectual copyright has expired. (Unlikely due to the relative newness of technology and the length of Copyrights).
4) If the source code is published by the developer for public use, and no part has been reverse engineered. (Usually accompanied with a GNU license)
5) If the source code has been reverse engineered with the permission of the developer.
6) If the main code is reverse engineered before 1999, and expanded privately for commercial or private use. This one was tricky but applied to a number of games that have private servers such as Ultima Online, Everquest and a few others. There seemed to be a loophole that many people were using that was upheld in a few courts because reverse engineering some software was not illegal at the time and allowed gifted coders to create their own servers but still use modified versions of the original software if it did not violate the terms of service of the original provider. Have you noticed that over the last 20 years you now have to click 'I accept' more often when installing/playing games than pre 1999? That's because of this.

I was really hoping for a nonsensical rebuttal when you were presented with a real argument.

If you had taken just a few minutes to do a bit of research as opposed to thinking you knew it all, you could have saved yourself a lot of time defending your false facts. Although it's not a great source, Wikipedia would have surely pointed you in the right direction as would the sites you mentioned earlier.

"Since the software is no longer sold or supported, the copyright holders are not directly harmed in any way. This is why abandonware sites are, for the most part, ignored by the law. The distribution of copyrighted software however is, and will allways be, illegal!"

"We allow you to download old games for free, but we do not take any responsibility for downloads considered illegal in your country. Please try to buy the game first : GoG.com, Steam, Amazon or eBay may be selling your game."

I do acknowledge that a lot of your opinion can come from personal experience and depending on where you live, this certainly can differ. A quick search of "Bulgaria piracy" shows quite a few interesting links so perhaps that could be at play as well.