If you've played a popular RPG like Pathfinder, Tales of the Valiant, or anything in with direct D&D lineage, then you know that there are at least two modes of the game. First, there's the roleplaying mode. When you're roleplaying, you pretend to talk to non-player characters and you make choices about where your character goes next to find adventure. And then there's combat mode. During combat, you put your miniature on a battle map, either literally or on a computer or just in your imagination, and you plan every move you make in 30-foot increments, making attacks against your foe's armour class, while trying to avoid being hit in retribution. For some players, both modes are equally enjoyable. But for others, combat is the best part of game night. And for still others, it's tedious micro-management of a scenario that would be better resolved with a coin toss.
If you're one of the people who loves combat as much or more than roleplaying, then you might also be a wargamer, whether you realise it yet or not. Wargaming, like an RPG, is surprisingly flexible, though, and many wargamers find that narrative play provides the same satisfaction as a story-driven RPG.
Buying a wargame is similar to buying an RPG. You primarily buy the rulebook, and you read it through to learn the rules. Because a wargame is essentially just the combat part of an RPG (actually, historically it's the other way round: the RPG was born from a wargame), the rulebook for a wargame is correspondingly focused mostly on just what happens on the battlefield. There are two major differences. First, instead of controlling one character as you do in an RPG, you control a whole army. Secondly, because the entire game is just the combat, your combat actions are more detailed than they are in an RPG.
Playing an army means you have to build (both literally and figuratively) an army instead of a character, but it also means that you have to think about the character of your army.
When you build an army for a wargame, you're deciding what kinds of military units you want to control on the battlefield. This starts with deciding on the size of your army. Do you want to control, for instance, 64 miniatures, or 16, or 8? Unit size differs from game system to game system, but if you're used to controlling just the 1 miniature from an RPG, even just 5 or 8 or 10 probably sounds a little overwhelming. In practice though, your army moves in "troops" or "units". You may be literally moving 64 miniatures across the table, but you're really only advancing 8 groups of 8, for instance. Each troop member is glued to the same square base, or else placed in a movement tray, so they all maintain unit cohesion.
You might logically wonder why anyone would bother with 5 miniatures when you could arguably just move 1 miniature and pretend that it's a cohesive unit. That's technically an option, but there are lots of reasons most wargamers prefer to represent each individual soldier. When your units consist of individual miniatures:
Once you know your target army size, you have to choose what kinds of soldiers (infantry, cavalry, melee, ranged) and wargear (turrets, battering rams, catapults, and so on) you want to include in your army. Your wargame rulebook usually specifies the options you have. There are rules governing how many of each thing you can add to your army roster. Some game systems use a point-buy system, with low-level troops costing a few points and really powerful ones costing a lot of points. Other game systems limit weapon types by count ("you can have X number of melee weapons and Y number of ranged", for example).
Building an army roster is usually done on paper (or in an app, these days) so you're sure to get the right mix of troops. After you've finalized your roster, you go out to your friendly local game store and buy the miniatures you need.
Some rulebooks are written for specific miniatures (Games Workshop, Corvus Belli, Mantic Games, for example), and others are generic and allow for interpretation. There are advantages and disadvantages to each approach, but this is a tabletop game so there's as much flexibility as you're willing to tolerate. Technically, you don't need miniatures at all. The game rules work with a paper cut-out just as well as they do with a bag of dollar-store plastic green toy soldier or a $50 kit of detailed wargaming miniatures.
The physical component of army building is so significant that it's its own cottage industry. Wargamers tend to be invested in assembling and painting the models representing their troops. It's a guarded and intentional "deficiency" of manufacturing. Miniatures for wargames are delivered unassembled so you can choose which head to put on which body, or which weapon to assign to which figure. They're also delivered unpainted so you can devise your own colour scheme for your troops, which isn't just a vanity project, because it helps distinguish your troops from your opponent's troops during a game.
There are people who enjoy this aspect of army building so much that they don't even play wargames. They just build and paint miniatures. Back when I was just an RPG player, I never used to paint miniatures because I thought it was well beyond my skills, but I've been pleasantly surprised as a wargamer that thanks to Contrast Paints and truly artistic sculpts, army building has become one of my favourite aspects of tabletop gaming.
If you're one of those RPG players who sits around building characters that you'll never play, or sketching out dungeons half of which you'll never run, then you can think of army building and miniature painting as part of the same never stop gaming ethos. Wargaming, like an RPG, doesn't stop after the table gets cleared off and goes back to being just a dining room table again. You can obsess over your armies just as much as you do over your RPG character builds, both by theorycrafting army rosters and by physically assembling and painting models.
After you've got your army assembled, it's time to play the game. Regardless of which wargame you've chosen to play, the rulebook tells you how a game is played. I think of a wargame in two parts: the setup and the combat.
Unlike an RPG, there's no Game Master in a wargame. It's just you and an opponent and the rules. The "game master" is the scenario itself. A scenario, whether it's called a "scenario" or a "mission" or "quest", is the reason your armies are fighting, and it usually includes an objective of that particular battle. An objective can be something vague, like "kill the enemy" or it can be something strategic to a larger war, like "secure Hill 242". You score extra points for securing an objective, whatever that objective might be.
The combat itself encompasses what you do during your turn. Because a wargame is just combat, the process for fighting in a wargame is typically more detailed than fighting in an RPG. In an RPG, you usually have four to six other players, each needing a turn, plus the Game Master, so combat is often designed to be relatively quick. I'm not claiming that RPG combat systems are actually all that fast, but there is usually room for roleplay before and after a combat in an RPG. Once the fighting stops in a wargame, the game is over, aside from possibly some recovery rolls and general army maintenance.
When moving miniatures in a wargame, you don't usually count squares the way you do in an RPG. The scope of many wargames is meant to be epic. You've got lots of troops covering lots of ground. Wargames usually measure movement in inches, using a ruler, because it's often presumed that you're playing on a very large table with no built-in grid. Movement in a wargame is often split into different types of movement. You might have a normal move, a charge action, a pile-in or melee movement, and so on. There's often terrain features on the table to move around. There can be traps and atmospheric effects that impose new rules or saving throws.
Attacking in a wargame rarely targets an armour class and instead offers, essentially, a saving throw. You roll to attack your opponent, and your opponent rolls to see which hit actually deals damage. You're usually rolling a lot of dice, too, because you have a lot of miniatures on the table. Attacks are often divided into different kinds of attacks using different skills and, accordingly, different dice.
The "health points" (HP) of a unit is typically a lot smaller than an RPG character. It's not uncommon to see a tolerance for just 2 or 3 wounds for each miniature in a wargame, sometimes less. One good hit in a wargame can mean death for a miniature, and when a unit loses too many miniatures the soldiers remaining may break rank and flee, pending a morale test.
Most of these concepts are roughly familiar to any RPG player, but usually each one involves, say, two steps instead of one, 7 or 10 or 15 dice instead a single d20, and so on. Everything's a little more complex, as if to pad out the gameplay but actually to help simulate the variables involved in a full-scale war. Trying to play a wargame using RPG combat rules would become frustrating pretty quickly. The abstraction of an armour class and the high numbers involved with individual HP doesn't translate to a big battle, so you deal with the details of your army, including weaponry, endurance, movement, morale, coordination, and of course strategy.
While wargaming doesn't involve roleplay, as such, that doesn't mean it lacks narrative. It can lack a narrative, if you don't want one, and that's liberating. A wargame really can just be a boardgame-style experience where you set up your troops and battle it out with an opponent, with no pretense of why these armies are fighting. However, it's equally as possible to structure a campaign of encounters held together by a story. And while you're thinking about what your army should do next, you are in a way roleplaying as an army general. You can narrate what a troop is doing as you move it across the board, you can rationalise its decisions. When your war machine, the one you thought couldn't be taken down, finally falls, you can tell the story of how and why the impossible has occurred. A creative player can generate a narrative around the game, and from the game's mechanics as they happen.
Some wargames have entire books of campaigns, with backstory and specific missions. Others, like historic wargaming, just use real life history as its narrative. And if you're the type of RPG player who loves coming up with backstories for your characters, or designing dungeons and adventures for other players, then you can invent your own scenarios and objectives for your armies to play.
There's lots of room for creativity in wargaming, and just because you don't have a character sheet doesn't mean you're not telling engaging stories set in a fictional world.
If you're an RPG player and you love the tense strategy of combat, you own it to yourself to try a wargame. You don't have to go out and invest in a collection of 100 miniatures. Go to a dollar store, buy some game tokens or a set of those cheap toy soldiers, and just try a game. I have several small wargames available on itchio and wargamevault.com, and I highly recommend Snarling Badger and Breach Storm.