In Heat Signature, a single wrong move can blow you out into the vacuum of space, while the right move makes you feel like a kung-fu genius.
It's a game with real confidence of design, where all the mechanics are meaningful and complementary to each other. It's also got a rather steep learning curve that, no matter how long you try to delay it, will eventually insist you not only learn every mechanic but master them.
Heat Signature immediately puts its best foot forward with a story-centric tutorial that takes you through all the basics of hurling yourself through space, hitting guards with wrenches and fighting your way in and out of enemy ships. In something like ninety seconds, the game perfectly conveys its tone and intent, alongside getting the player ready to learn the advanced techniques. But it only explicitly teaches the bare minimum needed to survive.
The fun is in discovering the rest for yourself. While the procedural generation means that no player will see the same items and have the same options in the same order, Heat Signature always offers a variety of mission types, objectives, enemies and difficulties. No tactical situation is impossible. Although I failed my missions frequently, I never had anything other my own incompetence to blame.
Every round begins by choosing from a list of procedurally generated missions with varying conditions, enemies and goals. Hijack a ship filled with heavily armored guards impervious to bullets in 120 seconds. Assassinate an officer while all the regular guards have heat sensing abilities and shotguns. Rescue a fellow resistance fighter in a giant sprawling map without being seen by anyone. Whatever my goals, the top-down view allowed me to see the whole extent of these gun-puzzle mazes immediately, and I could pause anytime to plan my approach.
Being able to pause freely and call shots allows for combination attacks that are limited only by inventory and strategic imagination. I could walk just around the corner of a hallway, pause, choose to fire a shotgun blast that takes out a cluster of guards down one end of the corridor, pause, pivot, and then leap with a sword to kill another guard in the opposite direction all in less than a couple seconds of real-time play. Inventory items let you control turrets, teleport yourself, swap places with guards, even blow up entire rooms, launching anyone in them (including the player character) into the interstellar void. The sheer variety of options, coupled with how fast the execution of a plan is once you’ve got one in mind, leads to addictive play-sessions where I consumed mission after mission greedily.
Heat Signature assured me that I'd be able to play at the level of difficulty appropriate to me as a player, and it took me several hours to discover that this wasn’t entirely true. Generally, the list of procedurally generated scenarios includes at least one that feels manageable and comfortable. As I got more familiar and handy with the game, that was around the “hard” difficulty level.
Here's the thing: My tactical imagination only carried me so far. Certain missions can be reset and replayed until you get it right, but the core progression missions will permanently kill your character if you fumble more than once or twice. If a character dies, the player can choose a new one with a fresh (mostly empty) inventory and pick up the overall galaxy progression where it was left off. That last part is key: having to restart the entire game on death would be way too punishing. But as it is, I still felt like the character permadeath system sucked a good portion of the enjoyment out of the game for me and didn’t respect the time I invested.
Heat Signature is intensely skill-based. Progress in the game is explicitly linked to how difficult a mission you’re willing or able to complete. An easy mission fills up a “Liberation Meter” maybe 10% where an extreme difficulty mission can fill almost the whole thing in one go. Early on, it's hard to grasp the scale of the game and its length, so it felt fine to content myself with easy and medium missions while I was getting the hang of it. It took me maybe half an hour to fill the meter the first time, and I thought I was making good progress. I was exceptionally wrong.
Winning the galactic war and bringing peace to the sector involves capturing four Strongholds. To unlock a Stronghold, ten individual systems have to be liberated. That means, if you only want easy missions, you'd have to play 400 of them to get anywhere. Easy is actually very easy, so I’ll assume most players are doing at least medium difficulty missions; you'd still have to play around 150 of them. And that's just to unlock the Stronghold missions. They're locked in at “mistake” difficulty (the hardest difficulty level), so even if you've been playing hard or the even more challenging “audacious” missions you'll still have to play at an even higher skill level to finish.
I spent 10 hours just getting to the first stronghold and then failing repeatedly as all my characters died. I don't know how long it would take me to truly master the game, but it eventually demands nothing less. And I didn't want that. The momentum that comes with the fast pace of the gameplay in most missions is its greatest strength. I was continually seeing new things, trying new things, surprising myself with what's possible. Then I reached multiple points where I was spending a whole half hour on a single mission only to fail, losing hard-won inventory and character progress. I would come back to take a newly generated but equally difficult stab at the missions again in another hour or so with my next character. And likely fail again. Then come back in an hour. It ground the game’s pacing to a halt for me.
There are options to get out of failure-state scenarios. For example, when I got tossed out an airlock, I was able to summon my ship, pick myself up and loop right back around to the vessel for another try. Some items do a delayed teleport — even if a character is unconscious and in trouble it can zip them right back to a safe room. Up through the ”audacious” difficulty level, this is all helpful and keeps the pace up. But each time I was kicked into the vacuum of space, my character’s tolerance for floating adrift was lowered. Eventually my luck dried up. When I really needed these systems of forgiveness on “mistake” difficulty they weren’t as available.
As I went about liberating systems, I was offered more and more mission conditions. These goals started out asking me to not kill anyone besides my target, and they ramped up the complications from there, with goals like being a total pacifist or an unseen hand. Mission conditions are technically optional — you still fill the Liberation Meter, and you can still win even if they aren’t fulfilled, but half the pay is cut. These contract riders make the puzzles even more engaging, but I saw the most difficult conditions a lot more often than regular ones. Frustratingly, items at the store are also only unlockable through Liberation Meter progress, which led to a mid-game slump where I was stuck looking at a wide variety of intensely demanding missions that I didn’t feel able to properly equip myself for.
At the average difficulty of the late game, where most missions on offer are “audacious” or “mistake” difficulty with complex conditions, the consequences of making a misstep are so severe, immediate and overwhelming that there's not a lot of getting yourself out of failure states. Not for me, anyway. I felt betrayed, given the promise of choosing my own difficulty. As I got deeper into Heat Signature, I frequently wasn’t even offered easy and medium missions. the game pushed me to do more and try harder. I'm a clumsy gamer from time to time, and I need a little room for error. The puzzles the missions essentially boil down to are all excellent, and for players that are performing at that skill level, I can see how rewarding it would be. You're given all the tools to pull off some astounding two-dimensional acrobatics. But the best of the game is reserved for the best of players, and the rest of us are left running a hamster wheel of procedurally generated content without being able to actually draw the game to a meaningful conclusion.
That's a shame because the story elements are pulpy and likable, with gruff space-opera characters giving light exposition and cementing the vibe. Each character has a 'personal mission', a procedurally generated goal that gives characters permanent bonuses. You have to pay 200 of in-game currency to embark on them, which can take anywhere from four to over a dozen missions to collect. The personal missions are also locked in at maximum difficulty. Thematically, this is totally appropriate: It's a climactic mission! But again, it ties success not just to understanding the mechanics but being able to execute them flawlessly.
Heat Signature is one of the tightest indie action games I've played, packing a maximum amount of excitement into a minimum amount of time and space. My first few hours with the game were genuinely wonderful, filled with rapid-fire moments of delight and triumph. But when I hit my personal skill ceiling, I could do no more than repeatedly bang my head against it. I respect Heat Signature. I admire its success in accomplishing with such skill what it set out to do, and if it had been more forgiving, it wouldn’t be as tense. Heat Signature’s laser focus on in-depth mechanical play with high consequence is at once what made it satisfying for me to play and what made it easy to put down and walk away from when I hit the limits of my tactical creativity.
Heat Signature was reviewed using a final “retail” Steam download code provided by Suspicious Developments. You can find additional information about Polygon’s ethics policy here.