XCOM: Enemy Unknown Cheats
1. Run XCom and make sure you're in base view.
2. Alt+TAB out, run Cheatengine.
3. Upper left corner, hit the flashing button.
4. Select XCom from the list, hit Open.
5. In the Value line, type your current amount of credits and hit First Scan. You'll see a lot of values on the left.
6. Go back into the game and spend some money.
7. Alt+TAB out again and in the Value tab enter your current amount of credits, and hit Next Scan.
8. You should see a single value on the left side now. If not, repeat steps 6 and 7.
9. Right click on it and select "Change value of the selected address" and just type in 999999. Hit ok, go back into game and spend some money to see it go to 999,999.