Anti-virus software will often flag software as malicious, even if its not. The idea is that this is better than not flagging some actual viruses as malicious.
As a developer, even compiling a “Hello world” program would sometimes get flagged by an anti-virus. This can easily happen if a developer is not very well known (yet), or if they don’t sign the software (at least on windows).
Having said that, this doesn’t mean everything is safe, just that having the anti-virus flag a game as malicious is not evidence enough.