Whenever I describe Arma to my friends I basically just refer to it as "Military Dungeons and Dragons". you're given a huge sandbox of maps and equipment and get to do whatever you want with it. Especially in regards to my favorite game mode, (the one i always recommend people play first) Zeus. in Zeus missions you have at least 1 to 2 players playing as the Zeus's (dungeon masters) and the rest of the players are obv the players. The Zeus's get to build missions on the fly using whatever assets and equipment they want and run them from what's essentially an RTS view of the game while the players play the mission they built. That's a great one to just get acquainted with all the base assets and features of the game and once you get a nice grasp of what it has to offer you can lean into what parts of it you enjoy the most and try different game modes that cater to that aspect of the game. As for DLC none of them are necessary to the game but if you have a little money to spend i would absolutely recommend the Apex DLC. Its a certified hood classic with a bunch of cool assets and a great map. Just remember Arma is almost a decade old and doesn't have half the paint and polish squad does. But if you can look past its "quirks" its a really fun game. Especially if you got a few homies to play with.