So, my first suggestion would be… play a lot of video games?
Okay, so, thing is, if you’re going to write about video games, you do need to know what you’re talking about. Actual violence isn’t something you’re likely to experience, but, if you’re building off video games; well, violence in video games is something that’s on tap.
Using just what you’re describing, the first recommendation that comes to mind is Fallout: New Vegas on hardcore mode. Hardcore doesn’t actually make the game more difficult, per say, it just enables some simulation like mechanics. Basic healing items only heal the player’s health, damage to limbs is persistent without medical attention, and starvation, dehydration, and sleep deprivation all become threats that you have to manage. There’s some writing in quests talking about more specific injuries occurring to other characters, even though the mechanics themselves don’t support them. (Fallout 3 lacks hardcore mode, so stimpacks will automatically heal limb damage, which basically negates that mechanic while you’re healing.)
If your setting is post apocalyptic, the STALKER games might be a good franchise to look at, even if they are brutally difficult. Character advancement is non-traditional, and I’ve taken flak in the past for calling them RPGs… but all three games fall someplace between an RPG, survival horror, and an FPS.
If it’s a modern setting, then some of the Tom Clancy titles, particularly the two Rainbow Six: Vegas games come to mind. They also don’t have any persistent damage mechanics, and are also extremely lethal, with a focus on “realistic,” tactical gunplay. It’s not, you know, actually realistic, but it’s also accessible.
If you’re looking at a fantasy setting then Dark Souls might be a good choice. It honestly isn’t has hard as some of it’s fans would have you believe. That said, it is unforgiving of mistakes, so expect to take quite a bit of time mastering the combat system. I’m actually going to come back to this one again in a second.
I think I’ve mentioned Mount & Blade before. I haven’t played the more recent games in the series, but it’s a sort of medieval version of Elite, where you build up a mercenary band and then go… do, whatever. Sign on with one of the factions, trade goods, prey on bandits. The mounted combat is really good, and it does mass combat really well.
If you’re wanting to go with a more cyberpunk setting Deus Ex: Human Revolution is worth looking at. The original Deus Ex is also, though the combat itself is a little wonky.
Now, this is all assuming you want a sort of real time, action game style combat system. If you want a more abstract system, looking at games like the Firaxis XCOM reboot, or Shadowrun Returns might be more appropriate. Also, on that subject, if you have a solid understanding of 3rd and 3.5 Edition D&D, Order of the Stick is probably worth a look.
Okay, that’s just writing combat… if you’re wanting to write about video games and RPGs, and play with the concepts there, you’re going to need a slightly different recommendation list.
I’d start with Knights of the Old Republic 2. This does some brilliant stuff with talking about mechanics like discussing leveling up as the player consuming anything they fought, and addressing how once party members join, they’re effectively stripped of their free will in service of killing for the player.
The developers revisited some of those themes in Neverwinter Nights 2’s first expansion, Mask of the Betrayer, and I would recommend that game, but it requires spending a lot of time getting through the main NWN2 campaign to get there. (Technically, you can fresh generate a preleveled character for MotB, but without having a solid grasp of the systems going in, it would be a horrible introduction.)
Dark Souls actually does some interesting setting stuff. Some of this requires digging around in the item descriptions and trying to piece it together… or just looking up YouTube videos, with someone else doing the musing. Marcus “EpicNameBro“ Sanders is probably the best in depth source out there, and VaatiVidya has some good primer videos. (Somewhat obviously, there’s a fair number of spoilers in both of those links.)
The one thing I’ll highlight that is really interesting to me is this: In Dark Souls (and the sequel) you play as an undead, and most of the characters and enemies you encounter are also undead. The mindless undead are called “hollows” and what differentiates the player character from hollows is that they’ve been completely broken by the constant cycle of death and revival. This isn’t an instantaneous process, and as the game progresses, you’ll see several NPCs who become increasingly despondent, until they ultimately go hollow. Without something to work for, they eventually give up the will to live. Which works as a fantastic metaphor for player burnout and fatigue, with hollowing being the point where you put down the controller and walk away forever.
The Saints Row series (particularly 3 and 4) are excellent snapshots of the psychopathic impulses of the average player, codified into dialog and decision making. For all the puerile jokes, the games actually have some surprisingly strong writing, so, if your setting has any inclination towards a GTA style, these are worth looking at.
I know I’ve mentioned it before, but Spec Ops: The Line is an absolutely fantastic tear down of your standard Modern Military Shooter protagonist. The game itself feels fairly generic, up to a point, but, if you want to present your protagonist as an actual person trying to deal with what they’re doing, this is almost exactly the opposite of the Saints Row games, so one of these should be useful to you, though probably not both.
Also, read The Metaphysics of Morrowind. This is a really interesting discussion on player agency, and the implications of it. Specifically, the author is talking about The Elder Scrolls setting, but the discussion on modding, cheat codes, and quickloads as part of a larger coherent multiverse is worth reading.
I’m also going to toss this link to Super Bunnyhop’s Metal Gear Solid 2 analysis video in here. This one might not make sense for a few minutes, just stick with it, you’ll probably learn something. (Also, obligatory spoiler warnings for a game that was published in 1998.)