I first got this game several years ago, and played a ton of it, and was pleased to find it was on Steam, along with its sequel (which I unfortunately haven't played as of yet). It's an enjoyable real-time pause-based strategy game set in a 40s-50s era metropolis filled with superheroes and villians.
Overall, the main appeal this game has (at least for me) is how much like a comic book it actually is. The writing is fun and incredibly campy (and revels in it), and very cartoonish, but it has its more serious moments too. The characters are all knockoffs of actual comic book superheroes and villians (though I didn't catch some of the parallels. Granted, I'm not well-versed in comics), but each has his or her own twist, and I found them all enjoyable, and while fairly cliché, they worked well. Personally I found the game to be hilarious, but I do enjoy some campiness now and then.
The gameplay itself, as I mentioned, is a mix between real-time and turn-based gameplay, with events happening in real time, and the issuing of commands done while the game is paused, though you can still issue some commands (such as a certain attack or movement) in real time as well. Sometimes the pathfinding is a bit clunky, but it works, and any little quirks can usually be fixed with a quick pause or micromanagement. The game also features many destructible objects (including buildings) for you to knock down, pick up, wield as clubs, throw, blow up, etc., all the better to dispatch the enemy henchmen with. Enemy variety and the simple aesthetic of the game make this all the more enjoyable. Something that also pleasantly surprised me (although I could just be bad) is that the game is fairly challenging, and a few moves can mean the difference between failure and success. It's not particularly brutal or anything, but it's not exactly a breeze, which is nice.
The game is structured in different missions (complete with a comic book cover loading screen, but with modern systems you might not have time to appreciate them), with several usually spanning a certain villian, before their inevitable demise. Between these missions, you have several different options to upgrade your heroes using experience you accumulate during the missions, as well as hire new heroes with a 'currency' called prestige which you gain from completing objectives. The most enjoyable part about this is that the game also includes a hero editor, wherein you can create your own superhero, and you may then hire them using prestige to play them in your campaign, though this isn't necessary to complete the game by any means.
As for the Steam version, I did have a bug when I attempted to play the game, in which the default left click action is set to attack and cannot be changed, meaning you can't click to move (though you may still move using the right click command interface). For me, this was fixed by verifying the cache, but this may not work for everyone. Keep in mind this game is over ten years old now, and you will likely have some compatability issues. From the sound of it, most can be fixed, but do be warned.
Overall, I found it a fun little romp through a comic book world, and I highly recommend it if it sounds remotely interesting. You can pick up both this game and its sequel in a bundle for the same price as one, so why not try both?