Local Mutliplayer without paying?

Hello there,
I’m developing a little top-down game in my free-time and lately is saw that it is now possible to write a mutliplayer game in Unity. Since I would love to play this game with my brother and my sister, I want to make my game multiplayer-ready.
The game will be played over a LAN connection, so one of us hosts the game withouth the need for an external server or any other services.
Now, is it possible to me to do that without paying anything? Are there any restrictions when doing so?

Unity supports networked multiplayer in the free version, but it is a bit of a pain to properly synchronize everything and get things setup using UNET.

Here’s a good link to get you started.

Developing multiplayer games with free version of Unity is extremely easy now, I changed my single player shooter into multiplayer game in just 1 hour.

I am/was kind of doing the same thing. Here is a tutorial to make a basic multiplayer shooter in unity.
Learn Game Development Without Coding Experience | Unity With the free version of unity, you can test/play a multiplayer game for free but with a limit of 20 people that are connected. So you can build and distribute the game to your family and play together, without having to complicate this and getting it all set up with Unity.