When the first of the Iron Man slots came out it was clear that the Marvel series from Playtech was going to be good (hence why you see a load of them free to play on this site! But the initial version and it's then-sidekick The Incredible Hulk were relatively low variance - meaning lots of smaller wins and not so many big hits. Built for entertainment first in other words. And a fine job they do too.
The Iron Man 2 slot was released to presumably address the imbalance because it's gone right he other way and joined the Great Blue game as one of Playtech's most volatile games. You have to be very patient on Iron man 2 - *very* patient! You can go 500 spins plus without the feature but when it hits it has potential.
We're talking about a free spin feature with a sticky wild on the center reel - bang in the middle. Not only that, but you have stacked symbols on all reels. Oh...and not only that, you have an increasing multiplier that takes you up to 6x over the course of 10 free spins. It's an excellent and innovative feature that just draws you in.
That's not to say the feature hits big every time. far from it. But to be honest if you get less than 50x then you've been unlucky and more often you'll get 100x plus. usually worth the wait but don't fall into the trap of thinking it will keep doing that. get out when teh going's good! A great game whiuch puts games like the Daredevil slot and the Blade game into the shade IMO.