Serviceable shooter, it's not anywhere close to the true greats of the genre, but it's all around not bad and fairly cheap, while kinda obvious this is the designer's first game.
So there are a lot of little issues here that we should go into first: is it a perfect game? Absolutely not. Not even close. Some really notable issues that stand out are things like the attacks from yourself and from enemies aren't really clear which is which, and it's very easy to lose track of yourself, even with your hitbox display turned on (which you have to do in options, it's not on by default). Part of this is a lack of colour-coding enemy attacks to be different from yours, but part of it's also that attacks from enemies can sometimes move backwards or change direction unexpectedly as well, so you can't just assume something is moving in a straight line away from you so you can ignore it and focus on another attack.
Part of the issue with the above one, is this is a combination of both a space shooter and a bullet hell, as those are two separate genres which look very similar but which behave very differently. A bullet hell has tons of projectiles laid out in complex grid patterns that you're supposed to learn the pattern of and focus on your ship to weave through the mazelike structures, and you ignore the enemies you're shooting at because they're so large they take up the whole screen. Space shooters have significantly fewer projectiles on screen, and smaller enemies, you spend more time aiming your shots and changing your movement to deal with enemies that shoot at where you're currently at, or evading homing projectiles. These two things do not really work well together because they're antithetical to each other's design spots, and the designer clearly didn't understand the reason why they work the way they do.
There are other issues as well, such as the procedural generation is not doing what the game claims. "You don't have to memorize the levels!" well, no, it's actually worse than that - is that enemy going to explode when it dies in a wave of bullets all over the screen? Well, you need to memorize what that enemy looks like, because they can show up in various different levels, and there's no indication from the enemy itself that it explodes on death, nor can you remember to watch out for that being a problem on this specific level. If anything, the way the procedural generation has been handled actually makes the memorization issue a lot more pronounced instead of less.
This is also an issue with bosses. The bosses are randomly chosen to a degree! ...But even if you have seen a boss before, its attack patterns aren't consistent either. Like the Scorpio boss will do a warning it's about to do a big AOE attack, where it thrusts its claws out and then a pile of bullets shows up where they're outstretched! ...But the specifics of that AOE attack differ each time you face the boss, the pattern you're expecting isn't consistent. I've yet to figure out if it's randomized, or based on how many levels into the game you are when you fight it, or some other function, but there's definitely different variations of the same boss that looks the same but behaves somewhat differently.
There are a ton of other issues like this, which will absolutely hold Operation STEEL back from greatness unless it gets a pretty major overhaul, and most games in this genre don't get significant content updates after they're released, so don't expect any.
However, despite that, it's a fairly solid game otherwise. It's far from perfect, it isn't one of the greats, but it's certainly not bad by any means. Weapons do feel fairly punchy, there's a good mixture of smaller enemies and mid-sized to bigger ones, mini-bosses and bosses to make different weapons ideal for different situations, and so you can feel the difference in a big weapon killing small and medium enemies instantly while a weaker gun might need 2-3 hits to take out a smaller enemy but fires much faster.
The various weapon types are pretty generic, just the standard ones you get in most space shooters. A charge beam that does a big, penetrating shot that goes through targets in a straight line but has rapid fire weak shots if you hold down the button for example, or a semi-homing laser, a charge laser that does more damage the longer you hold down the button, a spreadfire shot, a homing shot, a wave-based shot, pretty much just assume the standard guns you've seen in most space shooters are all present more or less.
(EDIT: Forgot to mention there's also a mechanic that if you stop shooting for about a second, you automatically pick up all the coins on the screen. ...This does not work very well with some of the weapons like the steady beam laser that grows stronger over time, or the charge up attack. Some weapons it's really useful for though, so it's kinda hit and miss)
There's a variety of passive weapons, on-use items which have a cooldown, and of course the generic "bomb" mechanic from most bullet hells, except you really don't restock bombs unless you buy them, which is baaaad for this kind of gameplay. Most of these aren't anything too special, though a few are kind of wrong for this style of gameplay, such as there's at least two side-ship options I've seen so far which spread out as you move back and narrow their targeting as you move forward, or shift up and down as you move, which really doesn't work at all with a mostly bullet-hell style of play where you have to focus primarily on your positioning, not looking at where your guns are shooting.
As stated, it has a lot of problems. It's not an amazing game by any stretch of the imagination. But it is a solid, fun game. It's fairly good for what it does, but go into this with the understanding that this is really only worth buying after you've played through games like Drainus, Tyrian 2000, Ikaruga or the Touhou series. Those are just flat out better games with much better design in general. But... space shooters don't last forever, and eventually you want to play more of them. So totally consider Operation STEEL after you've gone through the greats, I don't recommend it being your first space shooter, but if you've played all the ones I just mentioned, by all means, it's worth looking into as a fairly solid B-class title. It is not A-class nor anywhere close to S-class, but it'll definitely be worth a few hours of play. You can do better and cheaper, though. Do those first, then come poke at Operation STEEL after you've exhausted the others. It'll be fun when you get to it.
Overview:
Graphics: So-so, nothing special, but not too bad. Sorta cartoony, but it works. No real consistent theming though.
Sound effects: They work, they don't feel weirdly out of place, so they work well enough.
Music: Definitely not bad, but there's very few songs and they don't stand out. You do get a good feel for "Yay I want to shoot stuff!" but that's about it. It's never going to match the soundtracks for Touhou or Tyrian, though.
Gameplay: The moment-to-moment gameplay is good and does pretty much what you want. This is probably Operation STEEL's strongest point.
Game Design: It doesn't actually understand why other games do the things they do, and it shows. There's going to be a lot of minor frustrations all over because of a lack of comprehension for why various game mechanics don't work together.
Overall: It's good, but not great. Look to the greats first, then come back to grab Operation STEEL if you're still hungry for more pewpewing in space. It's like in the 6.5/10 range, definitely not bad, but has some very notable flaws.
