Should I approach the copyright holder and purchase a license, or attempt to buy the rights outright and transfer them to the open source project/myself/the original creator?
If the game company has gone bankrupt it might be a situation where the company was liquidated and its assets sold. If that is that case then the company no longer owns the copyright.
In any case I doubt it is worth purchasing the copyright. You state that you will be remaking this game from scratch which means purchasing someone else's copyright when you aren't going to use it will be a waste of money. Also you have to take into account that purchasing copyright is very expensive, requires a lawyer and at the end of it you can't really be guaranteed that you own it.
If you wish to use the original name then you should check and make sure any registered trademark has already expired. If it has then you should have no issue naming your game with the same name or something similar.
When making your own version of the game you should make sure that the names of things in the game, artwork, etc are all of your own work. This means they should be different from the original game. Copying how the original game plays shouldn't be an issue however.
If you feel that is not an option and that you need the original names of characters etc in your remake then you could have an expansion pack hosted someone else away from the project which adds the original content. That way if you do get in legal trouble you can pull the offending content without causing any problems where your project is hosted.