I've been playing RPG's off andon now for about 15 years, which actually frightens me a bit. I started with AD&D when I was young and an older cousin was visiting over some vacation or other and ran a short campaign for my brother and me. After getting thoroughly hooked, the vacation ended and the cousin had to leave.
There were a few groups of kids around just trying to start games, but I don't recall that any of them ever got off the ground. In frustration at the rest of the world my brother and I ended up taking turns DMing each other. As the older one I soon fell into the position of the regular DM.
This situation continued until the end of sixth grade for me. At that time (after acquiring most of the books available) I got tired of gaming. I had run several fairly long (for that age) campaigns and was bored of the same old stuff (mainly just killing bigger and badder monsters). I didn't end up playing again until I got to college.
In college I was introduced to the GURPS system and immediately fell in love with it. It had much of what I remembered AD&D lacked. I played a character in a campaign run by a friend of a friend and had a blast. I played a few more times before trying to brush off my old DM-, excuse me, GMing skills. It went well and since then I've gotten back into AD&D as well (the whole second edition thing was quite a revelation). For the past couple of years I've tended to have either a character or a campaign or both happening on a regular basis (once a week during school, twice during the summer).
Starting about a year ago some friends and I were discussing the various systems we had used: what was fun and what wasn't about each, mechanics, internal consistency, game balance, etc. Over several months these discussion turned into ways to improve the systems and the possibility of developing a new system.
I have spent quite a few lazy nights thinking about changes to make and finally started writing some of them down. Just a few weeks ago I started a new campaign using a HEAVILY worked over version of AD&D, almost a completely new system: reworked stats, stat modifiers, races, classes, weapons damages, weapons skills & proficiencies, other skills and proficiencies, etc. If it is a new system it very obviously has it's roots in AD&D.