It's hardcore in that unless you are familiar with the map layouts, objective locations and where the enemy is commonly found, you will die a lot and often, from all sorts of angles & directions you'll have no idea where they came from.
If you are coming from Counter-Strike Source and Team Fortress 2, you may want to first start out in a FireFight Match, which is basically a Team Deathmatch with no objectives.... this will help you get familiar with the maps, weapons and who is and isn't on your team (uniforms, runnging stances, etc.) while not having to worry too much about objectives & spawn count limits.
There are three different gameplay types:
• FireFight (Team Deathmatch)
• Countdown (Counter-Strike style gameplay with one life per round)
• Territory (Original RO Game Mode with multiple respawns & objectives to capture or hold)
Now depending on how difficult you want your game to be, there are three game modes:
• Action Mode (New Player Friendly - Reduced weapon damage, recoil & sway, crosshairs, More UI / information on screen, etc.)
• Realism Mode (Less UI / Information on screen, increased weapon sway, recoil & damage, lower stamina)
• Classic Mode (to represent elements & gameplay from RO1, even less stamina, more weapon sway, more recoil, hardly any UI / Information on screen, etc.)
Now as it goes for which game mode is more "Realisitic" or "Hardcore" that depends on the individual's preferences. Each game mode has certain elements that are "Realistic/Hardcore" while also having some elements that are not.
Some may think one thing is "Hardcore/Realistic" while another will think that thing is simply annoying and not realistic at all..... the debate can and does go on forever.
It is up to you to determine which game type you prefer and which game mode suits your tastes more.
I prefer Realism + Territory the most, while someone else will prefer Classic + Countdown..... and another person will like Action + FireFight..... or some other combination.