If, by some miracle, you find a key that actually works, the chances of it being legitimate are near zero. Many of these keys are purchased with stolen credit cards.
Once you have a valid key, you do not need a .txt file. You simply redeem the code on your chosen platform, and the game will be added to your library for official download and automatic updates. call of duty modern warfare 2 license key.txt download
If you're eager to play Call of Duty: Modern Warfare 2 but are concerned about the costs, consider the following alternatives: If, by some miracle, you find a key