Especially the unreal engine Epic Citadel demo.
Why do they waste time trying to move one of the most advanced and complex game engines to the web? A native UE3 game utilizes the full power of modern hardware. Even if they get JS to run at 50% of the native speed, it still is too slow for heavy games, but it will create the same CPU load, waste 50% energy and requires faster hardware.
Why not compile everything to brainfuck? It reminds me of that post of the guy who booted linux on an 8 bit uC :D