All these were tested with the launch command, "editor" in attempt to start up the editor. There may be other ways of launching them with a work around, but with the basic way of starting it up, these are what work and what don't work from my personal library of games.Works:SAW
works, but alas unofficial and missing some elements like Mirrors Edge, but still functional.Brothers in Arms: Hell's Highway
launches fine, not sure of functionality in the editor, but fist glance looks like it works.Don't work:All Points Bulletin
ignores it.America's Army 3.0
ignores it.Batman: Arkham Asylum
ignores the start up command and just goes to the launcher.Bioshock
ignores it. (Technically not really UE3 anyways)Bioshock 2
ignores it.Blacklight: Tango Down
gives the error, "Editor not supported in this mode."Borderlands
tries to start up, but crashes.Mass Effect
ignores it.Mass Effect 2
ignores it.Medal of Honor
ignores it.Moonbase Alpha
ignores it.Rainbow Six: Vegas 2
starts up the splash screen, but stops with an errors saying, "You are not running the editor from X:\Perforce, this may lead to problems. Please update your shortcut. The editor will be closed. If you have any question, contact Bruce Bellavance." Obviously an in-house dev notice which never got taken out.Rise of the Argonauts
makes the UnrealEd splash screen come up, but crashes. The Ball
gives the error, "Editor not supported in this mode."
So as you can see not many games, at least from my selection work. There are still a ton of games that can be tested if anyone has them, and they're on this list: http://en.wikipedia.org/wiki/List_of_Un ... l_Engine_3
Like I said maybe some of these have work arounds, but I've not researched into any.
Hope this helps.