I thought it was just Gold silver and modern, The way I was told to know the ages is by how superman fights. If superman is doing things like grabbing entire stars and pulling them around, That's Golden age, Limitless Superman, If Superman is leaping tall buildings in a single bound and bulletproof, That's silver age. And if Superman is getting his ass handed to him by doomsday, That's modern age. Like Legit, That's how I was taught to follow the ages. I had never heard of platinum age or bronze age.
WOW ! Gold Key. Don't remember that specific one but it took me back to the '60s as a kid. My grandfather worked for Western Publishing for 42 years. I remember going in to the plant and seeing all the house sized printing presses. He used to bring home comic blanks - no printing or staple - for me to doodle in. Somewhere in a box I have epic Starfleet battles drawn on that stuff. The tin roof of our old horse barn was a Western leftover - when you got up there and looked you could see an entire encyclopedia printed in it, backwards.
I never really read comic books much until early middle school when a friend turned me on to the Avengers and Marvel comics...That would have been around the year 1977... ...
And don't forget Total War (stories drawn by Wally Wood, although not the covers). Who were the mysterious invaders who launched attacks simultaneously across the globe?