My first computer as well! I remember typing game code from a magazine and saving it to the cassette tape. My big Christmas present the next year was the giant expansion box with the floppy drive.
Same here, I'm in the TI-99 as first computer club as well.
98% of what I did on it was just play cartridge games, but I did have a year or so of trying to type in Basic programs from library magazines. None of them ever came close to working since they were never for TI's weird dialect of Basic and I didn't know anything about the differences. Mostly what I did was CALL COLOR instructions for some pretty colors. I think the furthest I ever got with Basic was the "higher/lower" guess-the-number game. Eventually then we got a Tandy 1000 with GW-Basic and I moved on to that.
I didn't really get into Parsec. Tombstone City was my jam. And then I bought the Editor / Assembler package and it came with the source for Tombstone City as an example. It turns out the algorithm for figuring out which tumbleweed was going to turn into a monster was very simple. Reading that one bit of the source, I was able to predict where the bad guys would spawn and be ready for them. After that I could flip the counter and pretty much play as long as I wanted on two or three lives.
I figured that out just from playing Tombstone City. It's the first paired cactus by scanning the board in reading order (each row from the top, left-to-right.) (You mean a cactus that turns into a monster, not a tumbleweed.) And yes, once you know that, the game is pretty easy when you can anticipate every threat. I remember being able to go for at least a couple hours in one game; don't remember if I ever rolled it over or got bored before that.
