My rule of thumb is, generally, "Is the creator still earning from this product," and in the vast majority of cases where gaming software is concerned the answer is no. There is a push through sites like GOG.com to put many old games back on sale, but often it's through middle-men and holding companies and I doubt a dime of some of the more obscure titles goes anywhere near anyone who actually helped create the things.
The result is assorted holding companies picking up a few extra pennies, but a huge range of more obscure works are still the domain of abandonware sites and efforts like the Archive.
The result is assorted holding companies picking up a few extra pennies, but a huge range of more obscure works are still the domain of abandonware sites and efforts like the Archive.