Hello, I’m a beginner and I have trouble with replication. I would like to create a multiplayer game (survival) and I wanted to know if it is possible to first create a single player game, then take care about replication, run on server, etc… Or is it going to be extremely complicated? Regards
Adding replication to a single-player game sounds like a nightmare to me. The more complex the game, the closer to impossible you will get.
Multiplayer is definitely not something for new UE4 developers to attempt. Heck, there are many seasoned devs who still find it too much to deal with to be worthwhile. It would be a much better use of your time to learn UE4 without the complications of replication (IMO). But if you do, I recommend starting your project as a multiplayer game rather than porting it later.
Hope that helps.
Thanks for your answer, I will learn more about multiplayer then, do you know a guide or something that could help me with multiplayer? I have already done the “blueprint multiplayer series” by Unreal Engine, but i’m still not familiar with replication…
It’s kind of hard to find anything that shows you end-to-end multiplayer development. I had to learn piecemeal. Just head to YouTube, search for “UE4 replication” and treat it like you’re binge-watching Netflix. Skip stuff that doesn’t help but remember them in case they are relevant later. Along the way, keep your project in mind so you’re always hunting for things you will need. Maybe take notes – if you’re organized (I’m not). Then experiment and ask more questions here.
But most of all: treat this as a long-term project. Be patient. Be comfortable with being confused sometimes. You will eventually have an intuitive grasp on replication. After that you will be unstoppable. 
Thank you, I see this comment late but thank you for the motivation !
There are also some courses on Udemy about multiplayer in UE4, i’d recommend you go take a look there if that’s something you would want!