"Stole" the algorithm? Unless they had a patent on it, which AFAIK they didn't, it's not intellectual property to steal. (Under US law, at least.) On what grounds would they have a basis to sue? The actual issue was that they claimed to have a trademark on the use of "ARC" as a file extension. Despite the fact that there were known cases of that extension being used by other software before SEA's program was even written. My understanding is that P.K. decided to choose another name rather than fighting SEA. Which was legal, and would still be legal now (the DMCA notwithstanding). If this happened to me I'd work hard to make sure that my product offered a sufficiently good value proposition to the customer that it kept selling. If a product fails to do that, it *deserves* to be consigned to oblivion. Just because your product was selling well at some point at the past doesn't imply any god-given right or entitlement that it should continue to do so in the future with no further effort on your part.