No developer really declares their games as abandoned. like even games still under copyrights and patents that the company has ignored as a product that no longer can earn anything worth time to sell; could still come after you if you ran a popular game website that earns well on adds, that supplies their game as a free download lol.
its a judgment call based on money lol.
i think it is allowed here though.
like that transport tycoon game blocklanders play here. thats abandonware.