Once the CryEngine 3 SDK comes out in August or if it was September it will apparently be possible to create new.
(ToD stuff also at times and very little actual level editing.) This is set via CrySystem.dll or maybe CryGame.dll and with the editor using it's own binaries (The 64-bit stuff.) you can use the editor to play though it's a bit bulky but will allow all commands to work, I mainly use it to test commands on the fly though. cfg file for the set difficulty option, game options like g_godmode i_infiniteammo and what else needs to be put in afterwards but as explained the console is nearly entirely locked down with a few render related commands (But far from everything possible.) being unlocked. Game.cfg is also overwritten by any specifics in a level.cfg file for the loaded level and any diff_. (Also r_renderer works just as with Crysis 1 so it's caused some slight confusion, DX9 and DX10 is what it can be set to but there is no CryD3D10.dll file so what is loaded at DX10 is of course the DX11 related code.)
Game.cfg is also loaded relatively early (After system.cfg and autoexec.cfg) so certain low-level commands won't take or so I've understood it but since game.cfg is what holds r_renderer and that command being a low-level one it's probably false info though something to consider.