The reasons are:
1. The story, the characters and the classic humor of Lego games.
2. The types of heroes and villians. New (Guardians of the Galaxy, Doctor Srange, Hulk (ragnarok)) and old (Spider-man, Kang the Conqueror, Iron man)
3. The main villian … Kang the Conqueror!
4. The presentation of the levels by the hand of John Jonah Jameson.
5. Like in the other Marvel Superheroes games the constant cameo of Stan Lee.
And best of all:
6. The difficulty. In all the Lego games the difficulty is the same in all levels but in this game the enemies have got life bars.