Although you included 'Copyright' in the title of the thread, it is worth making it clear from the outset there is no copyright involved in the issues you have raised. Names are too short to be seen as creative literary works. You have pretty much shown you understand that this is largely a matter of trade marks.
You need to look at this from two perspectives. Firstly that you don't want to be sued by any other company over an allegation of infringing their intellectual property, and secondly you need to consider the potential damage to your product if the public are confused between it and that of a competitor.
If you register your existing company name at Companies House
they will check
to make sure it isn't the same as another registered company and advise you accordingly. But of course you don't have to trade under that registered name, you can adopt an overall brand name under which you trade. A good example of this is Dr Martens footwear which actually manufactured by a company called R Griggs Group Ltd
. In that way you can operate without confusing the buying public who will be largely unaware of the company name. There are some rules about this, mainly to be found in the Business Names Act 1985
and subsequent regulations which Companies House can advise you on. Basically company names are registered on a first come first served basis, although a very long established business which is not not registered may be able to challenge your registration if the company names are virtually identical. You can register your company through incorporation - normally as a limited liability company, or as a limited liability partnership. This is not really the place to go into the advantages/disadvantages of each. Also if the domain name you already own is based on your company name, having a registered company strengthens your case if a dispute over domain names should arise.
As the name of your game is going to be a major part of the branding process, you need to think hard about the implications of staying with a name which could easily be confused with another manufacturer's game. Do you want some of your potential customers to mistakenly buy the wrong product after you invest lots of money in promoting it? Do you want to run the risk of the other game getting a bad reputation and so affecting your game's sales? Even if you register your name first as a trade mark, that doesn't stop the other company from bringing out their game with the same or similar name (with the consequences I have outlined) and it would then be up to you to take some sort of legal action to stop them. This could be expensive, and the sort of distraction a young start-up can do without. Alternatively if the other company attempt to register the name first, you have fairly weak grounds for objecting because you have not actually been making your product available to the public during the past six years, so you have no prior reputation in the market place which is the normal grounds for an objection. You don't mention if the other game is also being developed by a large international company, but you need to consider their ability to fund litigation (if it comes to it) compared to yours. Sometimes these matters are resolved more by who has the deepest pockets, rather than who has the moral high ground!
And finally as you have not so far registered either the company or the trade mark, I suspect you may not have given much thought to securing the intellectual property you already own, namely the code in your game. You should draw up an agreement which spells out whether the copyright in the code, and any graphics which have gone into it, is owned jointly by the coders or is owned as an asset of the company. The law says that where an employee produces something in the course of his employment, the employer owns the copyright, but this may be difficult to resolve if your company is actually a sort of co-operative.
It will be essential to have clarity over this in the event that one or more members want to leave the team at some stage. Sorting these things out after the event is much more difficult than agreeing the details amicably in advance. Depending on how many people are involved and who has put backing money into the business etc, you may need to consult a lawyer in order to have an agreement which will cover all the relevant areas.
Good luck with your project