Yeah, Arma wasn't really my thing, I really like what they were trying to do, but the gameplay still felt pretty flimsy at times, too much simulation not enough fun. I tried Operation Flashpoint Dragon Rising or whatever it's called haha, years ago (torrented) and never wanted to try it again. It was actually better than Arma though because they didn't go too far into simulation, they almost had the balance right. I plan on trying Takedown: Red Sabre at somepoint, it looks like they've pulled off something different for the FPS genre, it's a cheap game too.
Well it was trying to sell itself as a military simulation rather than an action title. That really didn't work for single player though and even though I put a few hundred hours into it I never completed more than a couple of chapters in the campaign. There were some pretty great stuff though either breaking the simulation or using it to make it quite interesting and with some action.
1. DayZ...obviously. Lot of people got into it even though I was playing Arma 2 years before it and it seems like most of the 'vets' hated DayZ
2. Custom modes with a few friends. There were some pretty interesting custom maps which just a small amount of guys can do.
3. Mass organised online clan battles. If you haven't noticed a trend yet, all of these are multiplayer. When you have a large amount of guys doing organised events it is really cool. Yes, they take it seriously (some clans very seriously) but look up ShackTactical online sometime and you'll see what I mean. (Really love CHKillroy as a youtuber). All military language and procedures.
4. Benny's Warfare. This should go under custom modes but I really had to point this one out. If you don't have many friends this can be played with just yourself or maybe one other player. It turns the game into an RTS and you can opt to be the commander. If you're not, you are a squad leader and buy tanks, infantry or whatever for your squad. A friend and I had great fun just both of us being commanders and ordering the AI around though it is obviously better with more humans. Haven't convinced you? You can unlock a nuke after a few hours..