First programming I ever really did (in terms of understanding logic and its effects on end product) was Doom PWADs when I was a kid.
15 years later, I can get:
- Doomsday engine on my Mac
- 500MB of high-res textures hand-crafted to replace all the original walls and ceiling/floors.
- MD models for every object and monster
- High resolution re-sampled sound and music
- My original WAD - me and a friend made one of the largest (and highest tech - deep water, transparent textures on doors, invisible platforms) Doom II wads ever - lost it, but the internet still has thepath.zip
And play Doom II like I remember it, not like how it was.