What is it? It's a Diablo clone based on Marvel Superheroes. Which hero you pick is your class. Each has a unique skill tree and a unique set of items just for them, although most of the items follow the same pattern so they're not really unique, just a different icon because only a few heroes use a sword, for example. 99% of your drops will be for the hero you're playing.
The storyline is based on a series of chapters and hubs. Each chapter has a critical path to progress, and a bunch of optional missions that give you additional rewards, most commonly a 'reward box' with some random items and an Eternity Splinter. Eternity Splinters are important because they're how you unlock heroes beyond the first.
You can try out any hero up to level 10. This is maaaybe enough time to kind of get an idea of how much you'll like the hero. Maybe. It's also something like half an hour for any hero after the first. There are 49 heroes, and I didn't try very many of them because honestly I only recognize about half and most of the ones I recognized, I don't especially like.
I do like squirrels. They have a hero with squirrels. And more squirrels. Seriously -- two of Squirrel Girl's power trees are named 'Squirrels' and 'More Squirrels'. Also, they're not really trees. They're more like buckets that you pick things out of at random. Power heaps?
Unlimited free respecs! Yay! Also, 100% necessary because of the way your equipment gives you bonus powers and points in powers at random.
Being a diablo clone, you get to face RIDICULOUSLY HUGE PILES OF ENEMIES. Swarms of enemies. It's pretty crazy. Each enemy is pretty weak, though, unless...
Well, unless you don't stop to do something other than story missions and walk into chapter 7 at level 34. They made a VERY QUESTIONABLE DECISION to give you LESS XP if you fight something too strong for you. And also to not put anywhere what the recommended levels for the chapters are. Most guides suggest being level 37 or so going into chapter 7, and coming out at 44. I went in at 34 and came out at 35 because I got basically no xp for anything. Also, it was really hard and I died a lot because the bosses could one-shot me and the swarms of enemies were actually doing damage for once.
Fortunately, there are terminal missions which take levels from the story and adjust them to your hero at multiple difficulty levels and let you replay them for xp and special loot. So I'll probably be doing some of that for a while. That and the 'patrol' areas which have no storyline, but do have frequent zone events (like, every five minutes) where you get together and take down a huge powerful boss.
So, yes. You get to pick one hero to unlock past level 10 for free, and I picked Squirrel Girl because she's the most powerful (not really) and also has squirrels and more squirrels (her third tree is about her kicking people in the nuts). Also, she's optimistic and cute.
You also get 400 free eternity shards, which you can use to buy a 'team up' or pet or to unlock an additional hero (or two of the cheap ones). Instead, I bought 'random hero unlock' boxes which are cheaper than even the cheap heroes, and got Mr. Fantastic and Silver Surfer.
Mr. Fantastic is not as good as Squirrel Girl. Yes, he can punch all the way across the screen... with his weak punch that does nothing. All his stronger attacks are really short range. He's also not as cute, but at least he's optimistic?
Silver Surfer is powerful, but OH MY GOD THE ANGST. SO MUCH ANGST. Angst and Condescension. And self-doubt. Among his characterization are such diverse elements as angst, condescension, self-doubt, and an unwavering fear of Galactus.
But I played them both up to level 20 or so to get some more eternity splinters, and collected enough to get a third random hero box, out of which popped... Magneto.
SO MUCH ANGST. THIS IS NOT THE WAY TO LESS ANGST.