There are a lot of ways to answer a question like that.
Are you using purpose built hardware or older hardware, piecing something together, etc?
What are the requirements of the game server?
If you are just doing basic NAS/file sharing you can use below potato computer equipment and go with a free OS like FreeNAS, Ubuntu, etc. Of course, as requirements to run your operations (and number of) increase, so should your hardware ability. (obviously...I am getting there)
In my own case I tend to use purpose built or "last gen hand me downs" on a Win 10 Pro setup. I am familiar with the OS, it's easy to set up shares and such, can easily remote in from other Win machines, etc. Not to mention you can put it somewhere to be utilized for streaming, gaming, general PC use, or even a back up to the back up (lol).