I don't know all the reasons, but I will try to answer the ones I know:
Serious Sam: Double D
0 USD payment exploit on getgames
Dead Island
Steam Keys were hacked/leaked
Portal 2
Steam Keys were hacked/leaked
Puppy Games Keys
Free games given away on the developer's birthday by the developer. some people have taken more than the allowed 1 (and the 1 was for personal use only!) some of the exploited keys have already been revoked, see the puppygames blog for more information.
Dark Messiah of Might & Magic Multiplayer
(was) free on a polish gaming site
Eets (in certain amounts)
iPhone app exploit
Puzzle Agent (same reason as Eets)
The fact that they are forbidden here does not mean you can still get any of them for free.
You should not try to obtain exploited game keys, because many have already been revoked by Steam, others might get revoked in the future.
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You are still allowed to give away tradeable copies.
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Hey, newbie here. A quick search yielded nothing, neither did asking on the steam chat, so posting here instead.
My question is, does anyone know the reasons behind each game on the exploited list being there? I'm curious, as several of the games there are highly unlikely to be obtainable for free, given their profitability.
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