A turn-based tactics game gives you a squad, a grid and as long as you like to think. Each unit carries an action budget — classically one move and one act — and when the last of it is spent the enemy answers. Nothing here is testing your reflexes, so the only thing that can make a decision hard is what you have not been told. Every argument in the genre is an argument about that.
The board is an interface, and a good one answers your questions before you pay for the answers. How far each unit can move, drawn as a field of tiles. What each destination is worth: half cover, full cover, exposed. The hit chance on that target from that tile, updating as the cursor moves. Where the enemy can reach on its turn, and what it can see from there. Which of your units are watching which lanes — overwatch shown as a cone rather than promised in a tooltip. Height pays a bonus, flanking strips cover back off, and both are legible on the terrain before you commit a soldier to them.
The whole contract is the preview. You walk the cursor around, read the consequence of six different futures, and only then spend something you cannot take back. Fire Emblem's weapon triangle is the same instinct in miniature — swords beat axes, axes beat lances, lances beat swords, readable straight off the icons. Long-running rather than universal, though: Three Houses dropped it, so even the genre's most famous piece of legibility is a choice each game makes.
Fog of war, unscouted enemy groups, loadouts you have not seen yet. Concealment is what makes scouting a real action — a unit stepping out to reveal is spending safety to buy information, and that trade is most of what makes a first turn interesting.
Then there is the hiding designers do not advertise. XCOM 2 applies hidden aim assistance on its lower difficulties: the percentage on the screen is not the number being rolled, and only the higher settings stop softening the maths for you. It is a defensible lie — a player who feels unlucky keeps playing, and a player who feels patronised does not — but it does mean the genre's most famous statistic is, on most people's first campaign, a polite approximation.
The line worth holding is between withholding and ambushing. Hiding what you could have scouted is a design; surprising you with something no scouting could have revealed teaches nothing, and a loss you cannot trace back to a decision is just an interruption.
A displayed 95% reads as a promise rather than a distribution. You build the turn around it, the shot misses, and the plan that depended on it collapses in a way the nineteen hits never register. Chains make it worse: four separate 95% shots all landing happens about four times in five, so a plan resting on all of them fails more often than any single number on the screen suggests.
Into the Breach answers by deleting the dice. Every enemy telegraphs exactly what it will do before you move, damage is deterministic, and the turn becomes a knot to untie rather than a bet to place — with one rewind per mission as the concession to how tight the knots get. The trade is real in both directions. Perfect information makes a loss unambiguously yours, which is a cleaner teacher and a colder one. Hidden rolls buy drama and pay for it in save-scumming, which is what players do when the game wants a story and they want a puzzle.
The optimal way to play is usually the most boring one. Creep forward, hug full cover, overwatch everything, never take a fight you have not already won — the genre rewards cowardice, and designers know it, which is why mission timers keep getting bolted on and players keep hating them: the medicine is as unpleasant as the disease.
The better answers pull rather than push. An objective that moves — extract this unit, hold that ground, escort something fragile — makes advancing the safe play rather than the brave one. Reinforcements that arrive while you dawdle price delay without printing a countdown on the screen. XCOM 2's concealment pays you for opening aggressively, which is a bonus for boldness instead of a penalty for caution. And permadeath is the reason the timidity is rational in the first place: when the campaign layer keeps your veterans, every risk is being staked in a currency that does not come back. Take that layer away and you have a roguelite, where a lost battle is a lesson banked instead of a wound carried. Zoom out until squads are armies and turns are years and you reach 4X and grand strategy, which resolves in a single click the battle this genre spends an hour on.
Type: Turn-based tactics (a squad on a grid; a tactical RPG is this with named heroes and a plot)
Core loop: Read what the board admits, spend each unit's actions, end turn, answer the reply
Perspective: Isometric or top-down grid, with the information layered onto the terrain
Win / lose: The objective decides both; under permadeath the loss follows you into the campaign
Session: A mission in 20-60 minutes; a campaign is dozens of them
Progression: Units keep levels, gear and scars; the layer above prices every risk you take
Decide what your game will show a player before they commit, and what it will keep back. The classes, the cover system, the campaign bolted on top — all of it follows from that one page, and no amount of unit design will fix getting it wrong.