To a 10 year old Jimmy Impossible, Secret Wars was right in his wheel house. For one full year the best heroes and villains of the Marvel Universe would be together every month bashing skulls, having mountains dropped on them and bowing before Doom. Though the tie-ins were subtle, this was really the first huge company wide event at either of the Big Two. (sequart.org has a nice article comparing Secret Wars, Secret Wars II and Crisis on Infinite Earths and which is responsible for the rise of the endless Events that I keep getting suckered into, which seems like every few months.)
One of the biggest parts of Secret Wars, and in fact the reason for it’s existence, was a promotion for a toy line from Mattel.