From the official Store description:
Play as Captain America and lead your S.H.I.E.L.D. Strike Team as they struggle to contain a massive global attack by several nefarious criminal organizations. Stop the attacks and then take the battle to your enemies. Captain America must use all his tactical skill as he commands his Strike Team to combat threats on every front. Grow your agents into a potent fighting force, and when the odds are against you, call in Black Widow and Falcon to help turn the tide. Expose the villains behind these brazen attacks, unravel their plans and discover how the Winter Soldier fits into their scheme.
100% MARVEL EXPERIENCE
> An absorbing original story co-written by Marvel Comics writer Christos Gage
> Face off against iconic villains such as King Cobra, Taskmaster, Puff Adder, the Winter Soldier and more
> Art and graphics inspired directly by the comics
PLAY WITH YOUR FRIENDS
> Asynchronous multiplayer: Join a Clan and battle rival players!
> Climb the league leaderboards
> Earn cool rewards in Limited-Time Events
MANAGE YOUR BASE AND GROW IN POWER
> Enhance your agents and weapons for optimal performance in the field
> Learn new fighting techniques to supercharge Cap’s attacks
> Unlock and upgrade Captain America’s suits
> Research skills and items that help you advance faster
Note that you do need to be online throughout gameplay because of some of the in-game adverts and other elements. But the initial download is free, so you can't blame the developers for trying various ways of monetising their efforts. After the first two demo levels, in which you're more or less spoon-fed what to do, it's a 79p ($1) in-app-purchase to unlock the whole game (proper).
In which you can, in theory, progress right through without needing to buy further content, but freemium purchases speed up progress enormously. Here's the game in action:
Sadly the in-game graphics rarely live up to either the movie or the opening splash screen.... (right) eh? I suspect that this is code for 'downloading a few hundred MB of extra graphics and music' - the 'validating' stage takes many minutes, at least!
Ah yes, cut scenes to explain what plot there is. Which of these two would you take orders from? Discuss....(!)
Each mission has a few objectives, boiilng down to killing all the baddies while not using too many resources; (right) action in progress. POW! Tap to move, tap to hit, and note the extra SHIELD agents acting as 'wingmen' - they get hurt a lot though, and you'll be expected to revive them with medikits, so be careful!
More fist and shield throwing action - swipe on a enemy to throw the shield at them - don't worry, like a boomerang, it comes back every time!
Ah yes, man down. Time to use another medikit. So we've got kits, coins and now (right) 'tokens'? This is getting complicated....
Still, it's all slick enough to press on into the full game, which is bought (as here) in-app.
The full extent of the freemium scale then becomes clear. In addition to the coins and tokens, you can also buy credits, chips and consumables. Credits are the interface with real world currency, with a £3.49 purchase giving enough to keep gameplay going for multiple hours, which is probably fair enough. A top end of £31.99 is steep though - there should be a cap on IAPs, I reckon.
You can grab the game here - it's fair to say that it won't be everyone's cup of tea, but you can play the 2 level demo and decide for yourself?