If you made a level,Make sure there is no grenade,Bazooka type weapon in it.After that check if there arent placed more then 8 enemy's and not near eachother.(Due the fact they will turn in players)Then go to the File menu/Preferences and look at the bottom of that screen.It says:
()Singel Player () Multiplayer
Check multiplayer and press OK.
Then build your game* with all preferences you want and your game is ready and has other servers then other games.
MultiPlayer when no level excists yet:
Also go to preferences and check multiplayer and press OK.As you might see is that the grid you work on turns red.That's normal.After that you must not place more then 8 enemy's in it(That will be assigned as players)Also dont place any Bazooka,Grenade weapon in it.
if done build* your game.
NOTE FOR ALL MULTIPLAYER:
you cant use dynamic objects beside Players And some weapons.Also Sound zones hurt zones etc. wont work.
*= desiding on how many players you had put down you can assign in the Build game Screen under arena deside how much players there should be as max.Also you can set other settings you like.
Hope this helps all Noobs.
Master of the minds.
80% of the FPSC forums think tom0001 flames too much,i am one of the 20% who thinks he doesnt.