Another example is Hard Reset, which has a superbly optimized engine that was created by just a few people in the space of a year. I'm pretty sure they didn't have Skyrim's budget, but look up pics and tell me which game looks better.
Basically, I'm critical of Bethesda for not truly creating a new engine despite having massive financial backing. Meanwhile, my hero in Skyrim still jumps like a cripple in low gravity....