I know that Trilobyte, the creators of The 7th Guest, went out of business some time ago. Has their work entered the public domain in some way? If not, who owns the copyright for their works?
In general, if nobody official has said that the game – or any of the materials associated with it – is Public Domain, it is not. Copyright simply does not work like that; someone will own it as it is an asset of either the developer or the publisher (or, these days, their creditors or people that the creditors sold it on to).
I believe that works owned by a corporation automatically enter public domain 95 years after release or 120 years after creation, whichever is first. It used to be 28 years with a chance for one time 28 year renewal. They changed it in the 70s and added 20 years to it in the late 90s. The only way a game is in the public domain at this point is if the company releases it themselves.
Abandonware, however, is a concept which extends from the lack of enforcement of copyright by game companies which are no longer making money from the software. Since other answerers have said that it was just re-released, I somehow doubt they'll fail to go after you.
It should be noted that abandonware has no legal standing in the US right now. It is currently officially illegal to distribute games commonly considered to be abandonware.
A few years ago, the Library of Congress issued an exception for software only on media which is obsolete, but only as far as cracking DRM to archive the software with no allowance for distribution. This exception was for a period of two years with the chance for renewal, but was three years ago I believe
Note: I am not a lawyer
Trilobyte Games, and specifically founder Rob Landeros, have scrupulously maintained rights to all Trilobyte properties, with the exception of Clandestiny (the subject of a side agreement with Graeme Devine), over the years. Before the company was reorganized last year, the newly constituted organization headed by original founder Landeros & new partners Charlie McHenry & John Fricker retained the intellectual property practice of Northwest legal powerhouse Lane Powell Spears & Lubersky to ensure all intellectual property was properly assigned, ownership was clear, and no obstacles existed to the re-issue of 7th Guest and other properties. With that due diligence out complete, the titles entered the queue for re-release. Any inquiries regarding these matters are properly directed to Trilobyte Games, LLC in Medford, Oregon.