Stealth is always the best option with hardcore difficulty. Remain hidden and take easy kills. Waste no ammo and take advantage of free ammo. Possible achievement: Dj Artyom. On the level 'Outpost' reach the radio tower and broadcast the commander's message.
Metro 2033 (PC). Hardcore difficulty with no crosshairs. Enjoy. (Please note: this is not an achievement guide nor does it show all discovery points, hidden ammo, etc.)