Minecraft PC LAN but more "multiplayer" like!

I think there should be a singleplayer option JUST like lan, except there is only a 3 player limit and ANYONE can connect to it as long as they have the IP. for example, if someone opened it to lets say... Wireless Server Host.. WSH, and the IP became... 123.456.7.78:25565, if I gave it to someone lets say Morgan, then she can connect to the "Server" but its just singleplayer with a advanced LAN, but.. WSH!