I'm looking for a good offshore development company for my project, I have a great game project. What offshore company of developers could you recommend for a long-term project?

I agree with Tom, this question is not quite right, but I will help you. You need to identify your business needs for a new custom software. Consider all the existing problems and risk factors for the software development team with a clear vision. Inform them what kind of software you require for your business in order to simplify the complicated workflows that meet all your business prospectives.I'll only talking from my personal experience. You should do a LOT of research before any dealing. Try to get a more clear picture of behind the scenes by trying to communicate directly with the developers instead of the managers, almost everyone can understand English. I worked with developers from Eastern Europe, more precisely from Ukraine. If you think which company is best to choose, read this article https://diceus.com/free-report-offshore-software-development-rates-country/ I think it will help you

Let me outline the criteria that will help you on the way of choosing a suitable company:
1) Location. It determines the English level, the pool of tech specialists, time zone, work ethic, mentality, costs, quality of the work delivered, development rates etc. Discover the location properly in order to ensure all the criteria are satisfying.
2) Previous experience. Ask, whether the company has previous experience in outsourcing. If they have, address their customers to get a feedback. 
3) Business Overview and Credibility. Make sure your offshore software development company is able to provide your team with convenient work conditions(e.g equipment, office).
4) Project Management and Communication Tools. Communication is important. Learn what communication and management tools your potential vendor uses and whether they suit your business. Good luck!