There are a whopping 78 different characters to select from several different licenses: the Avengers, X-Men, Guardians of the Galaxy, and even the Netflix series The Defenders. It's developed using the OpenBOR engine and though it uses both visual and audio resources from games for 16-bit consoles, a large part of the content is created completely from scratch.
Marvel Infinity War is a free fangame set in the Marvel universe.