Works 100% with EU and TFTD. It is very simple to use, you just load your save with it and edit lots of values in game, depending on where the save is made from ie; battlescape\geoscape it allows you to change the values of all the aliens on the map, make them panic give them blaster launchers or just plain old kill em.
Problem is if you get greedy and have maximum bases all with 2 avengers with fusion cannons and 9000% fuel, it can get boring pretty quick. I try to use it to make fun scenarios. Like disabling the funding from the council (set max funding to 0) and trying to survive independently, (Inde-X-com) is also pretty helpful if you have Sebs extender mod installed for this as you can use auto sell functions for steady income.
Basically just use it to have fun.
You might want to back up your saves before hand but I have never had an issue with the tool before.
How to get it working.
1, Download from >>>here<<< (You can scan for virus's if you really want but I have downloaded it tons of times over the past year)
2, Open in winrar or any other archiver tool
3, Open README.txt and read (just so you know what's what)
4, Run XCOMHack3Install.msi and install to your hard drive (it in't necessary to plop it in your XCOM folder )
5, Run X-Com Hack v3.exe
6, Select the location for either your EU or TFTD game saves (mine is c:\program files\steam\steamapps\common\xcom\ufodefence) then open it.
7, Make changes to the game and SAVE before exiting
8, Play