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.
Stake is an Australia-based fintech startup that offers stock and ETF trading, regulated by the Australian Securities and Investment Commission (ASIC) and the UK's FCA. Stake provides stock and ETF trading on US markets at low fees.
Matt is the CEO and Founder of Stake, a purely digital brokerage offering commission-free trading of US Stocks and ETFs, the first of its kind in Australia.