Let's be real here. While that engine looks good, it doesn't really compare to the 4A engine. Look at the lighting. It looks Unreal 3 like. The lighting and particle effects in the Metro games are just plain incredible at times. My screenshots weren't planned out so I wasn't really able to capture it but you know about it because you've played them.
The way the fog, smoke, sparks, dust, etc move around in various lightshafts is the main reason why the games are so immersive.
Let's not also forget their proprietary form of AA which while in-game says that it's SSAA, is really some kind of mix of whatever they use. Point being, the end result is zero jaggies without SSAA performance drops. It's brilliant.
Zoom in on my screenshots. Doesn't it almost look painted on? Look at the grating on the car? Have you ever seen grating look that clear in a game? lol