Adjusted for inflation, it grossed around 1/10th that of a moderately successful game today.

The market was a lot smaller back then. The Sega Genesis/Mega Drive sold 33-40 million in total. Putting that into context, the XBox 360 and PS3 both sold 80-85 million units and the three main PS4 models sold 110-120 million, combined.

Today the best games sell to around 1/10th (and the very best, to 1/5th) of the total market, back then it was 1/50th for a strong game, and 1/20th for the best of their breed.

Not only was the market smaller, but people bought fewer games.