Games with lots of customization and creation?

[Lord Blade]

I've been itching for a game with a good system of item customization and creation.

I remember playing Alphaman way back when (when it was still new!) and having so much fun taking things apart and making new items.
And I always love games where I get lots of options when it comes to customizing and upgrading items (beyond just adding a +).

I was wondering what Roguelikes (and other games) are out there that give us that complex crafting system.
Extra points if it's a game where there's no "best" upgrade path or anything. I mean, something where you might get a dozen "end game" designs, instead of everything just building up to one final path.

Loves me my crafting.

Oh, and I tried... er... Xeno-something... where you're on a space ship and can build robots and such. That was kind of neat. But sadly very unfinished.

[dweller]

Unreal World has a crafting system which is interesting, as it strives for realism. You can make yourself weapons, cook various things and even make sauna! Lots of options there.

[Lord Blade]

I think I tried a demo of that game... and failed miserably at it. :p

[K.I.L.E.R]

Dwarf Fortress?

[Vanguard]

Check out Caves of Qud.  It's got a huge number of character creation options, and they all play differently.