Is it possible to make a server to be able to connect pc users to act like they are on the same LAN.
The purpose of this is to play LAN game when we are at different places. The maximum users would be 2 or 3.
The longer answer requires that you really know the difference between what is layer 2 and layer 3. You can make this work with a very special form of vpn called L2TPv3. It was mostly only supported on commercial routers but some third party router firmware images support it. It is still tricky to setup and put a large load on the cpu.
It is a popular free VPN application (free for up to 5 users), it is compatible with many games and have used it many times. Just set it up on your PC and point it to your server, then have your friends join the group and you can all access the server as if they were on your local network.