Yes, you can play both the campaign mode and multiplayer mode in Call of Duty: Modern Warfare 3 offline. The campaign mode can be played in its entirety in offline mode, and a Private Multiplayer mode allows you to access all of the maps and modes present in Multiplayer.
You can play the game offline, but there are several things you need to do first: Install MW3 via disc or download. If you're using a disc, you'll be prompted to download a 70+GB patch. If you purchased a digital download, skip to the next step.
As you've discovered, NOBODY is paying you big money just to play games or watch videos. Feel free to play those games if you find them fun (some people do) but do not play them expecting to ever get paid. That way, Google becomes aware of them and can work on removing them from the Play Store.
No Guarantees!\n\n Another reason I cannot call Spin for Cash a scam is because their Terms of Service doesn't make any promises. They can determine the availability and exchange rate for coins. They can ban you from using the service and cancel your rewards at their sole discretion. Tokens and coins are not actual money.