[fChk]

I didn't catch this thread from the start, but here is few tips to reflect on:

Is it possible to install libssl1.0.0.so on Centos 7? I left Centos long time ago because it is slow but if it supports my needs on my current server i can try it.

Yes!.. If you compile it yourself with the software it needs it... But I don't advise to do that for too many reasons that I don't have time to enumerate-just trust me on this :-).

OpenSSL v1.0.0 is deprecated long time ago, and so are the following: 1.1.0, 1.0.2, unless they are patched. OpenSSL v1.1.1 is the only actively supported version.

CentOS 6.5 is not working at all, even "yum update" is giving errors.
If you can, install Centos 7 to try then do it.

If you desperately looking for a TLS-1.0-compatible OS then CentOS 7 isn't the one you need but a CentOS version prior to 6.5 (6.4, 6.3 etc...) CentOS 6.5 didn't work because it already included OpenSSL 1.0.1 back then.

This goes to show you how obsolete that game server of yours is.

Just for the record, game servers are out of my scope of interests (never were and never will.) So can't comment further on this topic.