Ezt a linket elteszem az utókor számára, ha még egyszer találkoznánk ezzel a problémával:

http://gaming.stackexchange.com/questions/26664/how-can-my-friend-and-i-play-tf2-against-bots

A lényeg:

Here is an instruction on how to create a server and put bots on it:

1. Make sure you have the port 27015 accessible for connections.
2. Open the game console. (Options⇨Keyboard⇨Advanced...⇨Enable developer console. Press ~ / ` to open the console at any time.)
3. Type sv_lan 0 if you want the game to be public, or sv_lan 1 for LAN only.
4. Type map <mapname>, replacing <mapname> with the name of the map you want to play. Or press the [+] to the right of BROWSE SERVERS in main menu instead.
5. If the server is public and you don't want anyone to intrude, you can set a password: Type sv_password <pass>, replacing <pass> with some simple password. (e.g. sv_password 1234)
6. Set the bot difficulty: tf_bot_difficulty <x>, where <x> is from 0 (the easiest) to 3.
7. Add bots: tf_bot_add <team> <class> (<team>: red | blue; <class>: scout | soldier | pyro | demoman | heavyweapons | engineer | medic | sniper | spy.) To remove all bots: tf_bot_kick all

Here are some ways for your friend to connect. If one fails, try the next one.

• Join the game via Steam. (In Steam Friends list press ▼ and Join Game. In console: connect <ip>:27015, where <ip> is your (server's) IP address, e.g. connect 11.22.33.44:27015)
• Try the same thing with your (server's) local IP address (find it in Windows/Linux)

If nothing works, see the step 1 of server creation instruction.