Okay. Something major that I was unaware of:

Even earlier than Pinball Construction Set, which (text adventures aside) has popular distinction as the first game creation system, there’s a product for the Apple II and (later) Atari 400/800 computers called The Arcade Machine.

This is a tool for creating simple top-down shooters in the Space Invaders/Galaga mode, which seems rather narrow — but then so is a dedicated pinball design tool. Going by some screenshots, it also seems very flexible within those limitations.

The Arcade Machine was designed by Chris Jochumson and Doug Carlston, the latter being one of the two founders of Brøderbund. Yes, this is an early Brøderbund release — pre-Choplifter. That totally makes sense, and it also may explain why although reviewed well this tool has gone so under the radar these last thirty years — as this was just before Brøderbund hit it big and became a major publisher.

Also going by the back of the Atari box, it seems there was a contest where Brøderbund would reward the best user-derived game with a prize of $1,500 ($3,600 in 2012 dollars).

So much of videogame history has become obscure. And some of this stuff, you’d expect it would be fairly important.