omega_peaches said:
1) Do I have to have HL2, or can it just be source game?
2) If it's the source engine, can it be a demo, or do I have to have the full source game?
(Im asking this because of Goldeneye and Jailbreak)
1: You can own any source game to run
most Source mods. I say
most because some do require certain Source games in order to run (for example: SMOD requires HL2, SMOD Tactical requires HL2 and Counter Strike: Source, and so on and so forth).
Goldeneye Source I know doesn't require any specific Source game. Jailbreak I'm not too sure about, however.
2: It has to be a full game that you purchased and includes the Source SDK, which Source mods require in order to run. Demos and free source games that you might have obtained through a special promotion do not come with the Source SDK, so Source mods would not work.
omega_peaches said:
Also, if I download it, it will be it's own Icon on my wallpaper, right?
Some do, yes. Most require you to go into your Steam library and create a desktop icon from there.