Having developed games using a variety of technologies and platforms, I believe I have the versatility needed to construct your comprehensive FiveM server. My wide-ranging programming skills in languages like JavaScript, TypeScript, PHP, C#, Golang, Swift, Objective-C, Java, Kotlin paired with hands-on experience with web development and databases make me capable of delivering robust native and cross-platform apps - a skill set essential to build varied mini-games like Call of Duty and GTA.
Moreover, my expertise in designing multiplayer modes, leaderboards and tracking scoring mechanisms further strengthens my suitability for this project. I'm well-versed in implementing high-performance game servers while improving collaboration and workflows through tools like Jira and AWS. Not to mention my adeptness with integrating third-party SDKs like Facebook and Firebase which can help deliver your desired features like customizable characters, achievements, and more.
Let's collaborate to transform your vision into an outstanding reality!