ARMA: Cold War Assault is an awesome game. I was hoping to be able to finish the bundled DLC before reviewing the game, but it's fiendishly difficult and so I gave up, but the base game is fantastic if you like realistic first-person shooters.
I picked this game up when Russia invaded Ukraine (again), mainly because the game's campaign is based on essentially exactly that storyline. I am a fan of "one shot kills" first-person shooters and slow-paced/stealth games, and this game has a similar feel to it, plus vehicles and giant maps. I always knew of Arma 3 as being a "serious" military sim with a strong multiplayer and modding community, but I had no idea the first game also included a compelling single-player campaign.
You play the role of a couple of different soldiers defending a fictional East European country from a Russian invasion, and although each mission has clear goals and predefined strategies, it's also an open world that allows you to achieve the objectives in all manner of off-the-wall ways. This is a very old game so the vehicles in particular are prone to bugs and jank, but if your tank gets stuck in a wall occasionally you can still jump out, go prone, crawl around the whole map trying to find another vehicle or anti-tank weapon, then come back and take out your target and still finish the mission. And when you succeed in that kind of ridiculous save it feels amazing, because it's actually incredibly difficult to pull off, even if you do figure out ways to cheese some of the enemy AI. You can die very, very easily in this game, and that makes it so much more tense than shooters where you and everyone else is a bullet sponge. At the end of the campaign you get to meet up with a bunch of your squaddies and it really feels like you went through a war together - I literally teared up!
As mentioned earlier, the DLC is especially difficult, because a similar invasion storyline happens, but you are just a regular joe on the way to work. The campaign starts with you jumping on your motorcycle while the tanks roll in, and then you need to escape into the forest and set up a resistance unit keeping only the weapons and vehicles your team can salvage from mission to mission. I wish I could have completed it because it sounds like a fantastic storyline, but it's hard. This whole game is hard. Hard, but rewarding. If you want to play a fairly realistic military shooter from the last age of warfare before drones changed the game, you could do a lot worse than this.
One point I would stress is that the infantry experience is much better than the vehicles experience. In the main campaign by far the most frustrating missions are the ones where you need to drive a tank or fly a chopper to complete some timed objective. Usually with infantry-centric missions you can lean on your AI squadmates to back you up through tight spots, but with vehicles all bets are off. On the other hand, having vehicles on the battlefield does make it feel more realistic, and makes it even easier to get killed as PBI, which just ratchets up the tension further. Man, even just thinking back to my playthrough a year later has me thrilled. I think I might go wishlist Arma 2.