The only game I have every completed is FarCry. It was awesome and has graphics that still are one of the best. Crysis tried to recreate the same, but never managed that. Thanks to the engine ( I think it was cryengine ), FarCry managed to play on relatively low end machines too. That was added advantage and game was quite successful. I have completed that game twice ( Yes, I played back to back twice ).
Crysis ended up bringing even very high hardware to its knees and became a benchmarking tool, but the game is not very enjoyable even with entry level gaming PC.