You can start by looking at the examples to see how scripting works,
if you want to first test the gameplay idea you can start to play with simple meshs, like boxes etc
Networking is not easy to start with, you will probably need to learn c++ or to team with
a programmer for that. Step by step is good, first paper design (writing the rules, sketching...) then prototyping, and finally programming, network, modelling etc
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