Metro 2033
Set in the shattered subway of a post-apocalyptic Moscow, Metro 2033 is a story of intensive underground survival where the fate of mankind rests in your hands. And if you happen to enjoy your on-screen visuals, it's one of the best-looking games we've seen in recent years.
The very toughest of games engines can make it falter, however. Bear in mind you'd need to spend significant money to bring average frame-rates up to scratch in Metro 2033.