[Drunken F00l]

On a side note, I found out how to make Steam games... Non-steam (You have to own it, though.)

Anyway, make sure you put it in the folder that has the Hl2.exe in it.

Make a .bat (batch) file with the command HL2.exe -Game <Game>

Example:

Code:

x:\...\steam\steamapps\Username\team fortress 2

You would put "team fortress 2" after "-game". It should look like this:

Code:

hl2.exe -game team fortress 2

This is almost certainly incorrect. The -game won't work with spaces, and specifies a path relative to the hl2.exe/your working directory. Hl2.exe is actually in the team fortress 2 folder, so the correct thing is hl2.exe -game tf

Still not sure that's going to do it for you. If you're interested in running TF2 outside of Steam, this is relevant:
http://www.mithun.org/solus/tf2_demos_easymethod.pdf