if i am a professional , can i create a CallOfDuty4 by 3DGS?
my friend say to me : you cant.
Are you superman? I mean, CoD4 is a big beast of software, tons of assets, scripts, thousand hours of work by a team etc...
There are so many parts you need to get done right, for instance the engines scheduler will slow your game down which means you need an alternative. A good one would a balanced binary tree for your games regions and then a linked list for all entities in this region. Plus code for entity handover etc. pp.
You need to know about data structures and the algorithm needed to work with the them. You need to know about state machines for the AI. You need to know about pathfinding for the AI... etc etc etc etc.
Its not just only a hard task but also a impossible one for one person.