Comparatives and superlatives can often be confusing for students, they can mix up -er and -est. But this game gives them practice.
Role the dice, as normal. If they land on a adjective (i.e. small, big e.t.c) they can name something that is small or big e.t.c. If they land on a comparative (i.e. smaller, bigger e.t.c.) they can name one thing that is smaller or bigger (or another comparative) than another objet. If they land on a superlative (i.e. the longest, the biggest e.t.c) they must name two things and say which is the biggest/tallest/smallest e.t.c.