Into the Breach

Back when I didn't have money, I pirated this game and played the hell out of it, and it was one of my favorites to just boot up and do a turn every now and again in the background while I did other stuff.
Now that I actually do have the cash to spare, I made sure to get it officially to support the devs. But when I booted up the official version for the first time, it remembered all of my achievements and saves from my pirated copy, and gave them to me properly on steam. They really didn't have to do that, but they did, and I can't help but respect that whether intentional or not, they managed to make the swap to a legit copy as painless as possible. And they really didn't need to. So good on you.

Imagine playing chess against a computer. Now imagine the chess pieces are mechs vs aliens. Now imagine that your knight can push pawns out of the way and set them on fire. Now imagine your rook can shield itself and ram into other pieces to knock them down holes. Now imagine this is roguelite style and with each successive game you can upgrade your pieces to do new things - maybe now your knight can set smokescreens! Maybe now your rook can control their queen to attack their bishop!
That's essentially this game. S-tier roguelite for chess lovers, can be very hard at harder difficulties and easier at lower difficulties, very well balanced. Meta progression system is very fun - unlock new squads that do different stuff by getting achievements (which are often cool trick shots in a run). Low stress turn based that rewards thinking through the moves thoroughly. If you like chess and you like roguelites, then this game is the GOAT.

Did you like FTL? If YES, this game is for you.
Do you want something you can pick up for 10 minutes whilst waiting for the oven to warm up? If YES, this game is for you.
Do you want something you can obsess over the actions and turns for hours at a time without noticing it is dark outside and you really should go to bed as you have work tomorrow but you really want to finish the timeline? If YES, this game is for you.
Do you want to be the next Fortnite Twitch Stream Superstar?
Get over yourself, and get this game instead.

The closest a game has ever come to being "perfect."
Recommended (10/10)
Into the Breach is what happens when you strip every ounce of "fluff" away from the strategy genre until only the pure, diamond-hard mechanics remain. It’s a game of 8x8 grids and 5-turn battles where every single click feels like a life-or-death decision.
The Genius of the Design:
Perfect Information: Unlike almost every other tactics game, there is zero RNG in the combat. You know exactly where the enemies will move and who they will hit before you take your turn. If you lose, it’s not because of a missed 95% shot—it’s because you were outsmarted.
Collateral Damage: Your real health bar isn't your mechs; it’s the city buildings (the Power Grid). This shifts the goal from "kill all enemies" to "mitigate the disaster." Sometimes, the best move is to physically push an alien into the path of another alien's attack to save a skyscraper.
The "One More Turn" Loop: Rounds are bite-sized (usually 10–15 minutes), making it the ultimate "just one more run" game. With the Advanced Edition content added, the variety of squads and pilots is staggering.
It is a masterclass in economy of design. Every pixel and every rule serves a purpose. If you have even a passing interest in strategy, this is mandatory.

I have spent hours looking at the screen trying to determine if multiple different moves actually achieve an optimal result... without ever making a single final action. It's like a game of chess if the opponent was aliens and you were defending 5 different kings. A masterpiece that I am still trying to master.

My ideal tactics game, or very near to it.
I have played a lot of XCOM (2012). One of my biggest gripes with that game is my same gripe with Civ games and Total War games: The campaigns are very long. What this means is that you can play for 15 hours, survey your surroundings, and realize you've done everything wrong in a big way, and want to start over from scratch. Worse, even if you've laid your foundation well on a macro-scale, tactical blunders can amount to enormous setbacks (Oh no, my elite squad was wiped out because of some really unlucky dice rolls and now half the council is pulling out!), meaning tiny errors can amount to enormous losses in time. This does not feel great if you have a very busy life. The solution is savescumming, which fixes issues but removes a lot of the tension that makes tactics games interesting.
Most Tactics RPGs, on the other hand, have a similar works-every-time solution to all challenges: Grind. Whether it's for XP or items, all complex tactical puzzles can be solved with grinding. This can close off interesting tactical designs and decisions, since it's never clear how much grinding gives an achievable, challenging game experience until after you've completed the game, and the fact that it ALWAYS works encourages grinding as a solution.
ItB dodges both of these problems with a simple solution: Just be a roguelite! Playing out tactical blunders is way easier to stomach when a game is 3 hours long. Try out different strategies. Get silly with it. And get punished harshly for it! It feels way better to try and lose when trying and losing is the core gameplay loop, and it means you don't have to play safe, or savescum, or grind, and you can just relax, ponder interesting challenges, and have a good time.
You probably already know ItB's central gimmick: Your objective is not to defeat all enemies, but to protect buildings and complete objectives, making battles into puzzles where using your mechs to soak up damage is frequently a good decision. In fact, as a general rule, your first priority should probably be keeping valuable characters alive, and your SECOND prirority should probably be completing all objectives, which is important because perfect islands (where you complete all objectives) carry bonus rewards that will make further islands more survivable. Protecting buildings (and civilians) should be prioritized just below those two, and killing Vek should never be a top concern (although blocking them from emerging almost always pays dividends).
But another feature of this game that gets less attention is Subset's general unlockable design philosophy. Unlike some games where new playstyles are unlocked through victories, or in game currency, Subset's games unlock things using achievements. In ItB, these unlockables are new squads of mechs, each with their own unique starting equipment and playstyles, AND their own unique set of achievements that can only be unlocked with that squad.
The impact of this design decision is to encourage experimentation and trying different playstyles. Each squad starts with unique abilities and synergies, and the achievements guide you towards experimenting with them. There are also general achievements that reward regular progression and improvement at the game, as well as encouraging unique challenge runs. Grinding out achievements can be as interesting and rewarding, or even moreso, as simply trying to score a victory on the next difficulty level.
The final thing I like about ItB (and FTL before it)--there is no pretense of perfect gameplay balance. Some squads are better than others (Frozen Titans are POWERFUL on lower difficulties). Some missions are harder than others. Some enemies will fill your heart with fear, and others will make you sigh in relief. In other games, this would be very annoying, but in a game where losing progresses the game rather than erasing progress and is an integral part of the experience, and the real fun comes from making interesting decisions while you play, taking the focus away from perfect balance allows the devs to experiment and provide interesting and unique squad options which, while maybe not being as powerful as the next squad, are at least new and interesting.
Really, I can't recommend it enough. Like FTL, ItB received a MASSIVE free update adding buckets of new content years after relee, and the game has an enormous amount of content to explore. It's an endlessly replayable puzzler. It doesn't get as much love as FTL, and I can't understand why, because it's far and away my favorite of Subset's two games (and I really love FTL).

One of the best, turn-based deeply analytical games I have played! Awesome. No combat luck involved. Great replayability.