How far I can go in order to open source the project which is based on closed/commercial project where the whole source code (assuming the access is there) has been converted into different state or programming language (either manually or automatically by transcompiling)? So for example no single line (or resource) matches the original one, then who would notice that it was transcoded?
Under what (if any) circumstances can such a project be released with an open source license?
Few simple examples: OpenRA, OpenTomb, OpenTibia, however I'm not sure how relevant they are, as they're complete remakes.