You can choose to play as any character including Iron Man, War Machine, Thor, Emma Frost, Captain America, Hawkeye, and Hulk. Each has their own attributes and special moves, as well as a few characteristics that make them unique.
For example, Hulk has better health and stronger attacks than other characters such as Iron Man. But of course Iron Man, in contrast to Hulk, can use his suit to fly around.
Like pretty much any traditional beat 'em up, you'll find tons of normal enemies around the levels of Avengers United Battle Force as well as your typical final boss at the end of each level. Of course, you can also collect items that will give you more health and points.
Avengers United Battle Force is a fun action game in which you can enjoy playing as some of the most charismatic characters in the Marvel universe.