Fun thread; lots of interesting stuff in here. Multiple kinds of interesting. Haha.
That looks very nice, at least!
2 players Space Invader... the second player is on the top of the screen... you suppose to help each other kill all the aliens without killing each other... and then you kill each other...
This is actually a really cool idea.
As a kid I perceived programming as some recondite sorcery, and I assumed knowledge of it was absolutely required to make games. So, while I had interest in computer games, I mostly made board and card games. But one day my dad showed me how links worked in Microsoft PowerPoint, and I learned how I could make "buttons" out of any image I wanted, and have them navigate to specific points in the presentation. It was pretty mind-blowing at the time; I immediately understood I could use this to make games. Obviously anything that happened had to be a specific event I had prescribed and there could be no real concept of variables, but the potential was there for branching possibilities, so it worked well for quiz/trivia/puzzle ordeals as well as adventure/maze sorts of games. I tried quite a few things and left plenty of projects unfinished, of course, but I did finish some. I don't remember the first real game I finished, though, and I lost all that stuff.
After that I got into modding existing PC games (Civilization III was a big one), then into OHRRPGCE, and eventually Game Maker. The first game I finished in Game Maker was a pretty bad scrolling shooter with ugly graphics that used too many gradients... but they were all my own work, at least, and so was the music, so that counts for something, I guess. I remember I was also pretty proud of some animated GUI element; I don't remember if it tracked health or score or what. I still have the game somewhere (it wasn't even all that long ago, 2006 maybe), I think; maybe I'll dig up a screenshot later. But, yes, I look at it as sort of a landmark game for me, even if it wasn't technically the absolute first.
Sorry; I rambled on for longer than I meant to.

EDIT: Screenshot.

2007, it turns out; ugh, that's actually embarrassingly recent, and it somehow looks even worse than I remembered. I don't even know what to say now.