That's why I don't go for upgrading every 1-3 years. Most of the heavists games all suck, you play once, enjoy all the eye candy and then poof, forget it. And that's why I map for old commercial games that went open source, like doom, duke3d and quake.
Like Unreal powered games, all maps are free to open, inccluding its map contents, to see how things were done. Thanks God nexuiz is full open source, all its maps comes with the map file for you to see how maps are before compiling it.