So I've been playing around with the nice lead that atoric has given us here :
Here is a way how to mod this game.
Full copy of file "DefaultGameCore.ini" is stored inside executable file ...Binaries\Win32\XComGame.exe and game uses it instead of one in folder ...\XComGame\Config\
You need to use resource editor over XComGame.exe in order to modify DefaultGameCore. You need to look inside RCData section for resource 1020, which uses language 1033.
As for test I modified this line:BalanceMods_Normal=(eType=eChar_Soldier, iDamage=0, iCritHit=0,iAim=0,iDefense=0,iHP=5, iMobility=0,iWill=0)
Now I have 11 HP for all my soldiers. So such modding approach works, though it is not easy.
I use freeware Resource Hacker for editing resources. First you need to save 1020 resource in plain txt file. Then modify it. Then replace using such parameters:Type: RCData Name: 1020 Language: 1033And finally save file.
I hope it will satisfy your needs for a start.
It can be even simpler than that : you can perform searches and modify things directly in Resource Hacker if you are so inclined.
So with that, I went on a search for the Second Wave options (of which descriptions were found in the demo files; these are advanced options that can be activated after a first full playthrough, supposedly). Mostly because I did finish my first playthrough and found no sign of it in-game.
That search ended approximately 2 seconds later, as a search for "second wave" revealed a not so cryptic "ENABLE_SECOND_WAVE = 0" line !
I turn that 0 into a 1, and voila ! A wild Second Wave sub-menu appears in the new game menu !

Although the menu itself is a bit buggy (click to check boxes does not work so it needs to be navigated with the keyboard; Second Wave button disappears if Advanced options is used) after a few tests, it turns out that these options are fully functional

I would upload a screenshot but I'm still a bit hazy about the rules concerning that matter on this forum (just joined to say this, and hopefully become part of the community for this game I already love dearly), so I'll refrain for the moment.
The available options are Damage Roulette, Red Fog, New Economy, Not Created Equally, Hidden Potential, Absolutely Critical, The Greater Good. I have confirmed they are working for all except Red Fog and The Greater Good.
Unfortunately, the others that were mentioned in the files found in the demo are not selectable on the screen. Most notable Marathon, which is the one I was looking forward to the most.
However, the code in the .ini/ in the .exe (same thing) also has this just under ENABLE_SECOND_WAVE :
SW_FLANK_CRIT=100 SW_COVER_INCREASE=1.5f SW_SATELLITE_INCREASE=1.45f SW_ELERIUM_HALFLIFE=24 SW_ELERIUM_LOSS=0.05f SW_ABDUCTION_SITES=4 SW_RARE_PSI=8 SW_MARATHON=4.0f SW_MORE_POWER=2.0fSome of these options are clearly related to the missing options like Marathon, Blitz, Diminishing Returns, etc.
Problem is, I have no idea how to activate these or if it is even feasible.
Unfortunately my modding skills peak at doing a text search and changing a 0 into a 1...

Edit : here are some shots of the menus

Edited by PepprmintButler, 11 October 2012 - 02:13 PM.