The trouble is that the company may not own the rights to everything involved. This has been an issue for some companies that have tried to open up old games. S

The trouble is that the company may not own the rights to everything involved. This has been an issue for some companies that have tried to open up old games. Sometimes you have libraries, like Bink video (infamously) that are licensed and are not compatible with open licenses. There might be issues with the game engines or with assets. e.g. it's not uncommon to have music licensed for use in the game, but the rights don't include redistributing in other forms or producing something like a soundtrack. Stock music often has licenses that allow use in something like a game or movie, but disallow redistributing the file. (That was a sticking point for Bioshock Infinite: they produced their own new arrangements of some popular songs, but didn't have more costly licensing necessary to release a soundtrack.)