I think the first one for me was The Oregon Trail followed shortly by QBasic Gorillas and Nibbles. It was my first step in coding beyond Turtle Graphics on an Apple from even earlier in childhood.

Opening up the QBasic source code was eye opening for me: that computers weren't the realm of hackers typing incomprehensible text on TV and swapping floppy disks, but something that could start to make sense. My TRS-80 came next, and, for me, the rest was history.

Good memories. I wonder what the memories will be for kids right now in the age of LLMs.