I have been thinking… Would i be able to make a Game that in Multiplayer allows people on Lets say Xbox 360 play with people on PC?
I feel that it would be vary possible, It would be server side work wouldn’t it?
All 360 network connections are encrypted, such that a 360 can’t connect directly to a PC (or vice versa). You’d have to arrange to route the connection through Microsoft’s proxy system.
Well, unless you have a console license, you can’t make a console game. 
Fortunately for you, however, Unity DOES have a cross-platform multiplayer plugin. It’s called Photon. Look it up, it’s awesome. It works for all of Unity’s currently supported platforms.
Ehm, photon third party (not part of Unity package).
Also you cannot use it with Xbox360 directly, since photon does not support xbox360 (look it up).
Yeah, I should have mentioned that it’s a third-party plugin. But yeah, it works with Unity. Not too terribly surprised about the 360, but then again, it’s not like any of us are developing for it, right? Other than consoles, Photon does support all Unity-supported platforms. Assuming OP wants just general cross-platform capabilities, not specific from 360 ↔ PC, they should probably take a look at Photon.
Its something that is rarely done tbh.
Main reason is pc gamers would tear strips off console gamers in any FPS. This is not generally limited to FPS though, although at least with other types the advantage (keyboard/mouse) is less.
Okay, you get the console controller and I get the kb/mouse, now let’s go play starcraft…