Okay, here's definitely the best game I programmed in high school -- Dungeons Dank and Dismal. This one was done in Java and features some actual high-tech non-ASCII graphics. It's a Diablo-style dungeon crawl game with some relatively sophisticated features, such as randomly generated dungeons, automapping, enemies that follow you around, a shop where you can buy better items, and an actual final level. Best of all, you can play it right in your browser right now:Dungeons Dank and Dismal
Oh yeah, there are some bugs. I went off to college and got busy with classes and stuff, and I never really got a chance to debug this game or balance it properly. The most annoying thing is that it won't let you buy the plate mail armor even if you have enough gold. Another really irritating bug is that sometimes the climactic last level is completely devoid of monsters -- no idea why that happens. The dungeons are random, so sometimes it just so happens that the game is really easy and sometimes it's impossible. Also, every once in a while the game throws out a dungeon where large sections of it are completely cut off and inaccessible. Even after you pick up a key, the game will continue to announce that "you've found the key" every time you pass over that square. Last but not least, the monsters can't walk over any square where a monster has died -- though maybe that's not a bug and the monsters are all just really superstitious/deferential toward the dead or something.