Actually for immersion, the original PC Harpoon took some beating. I remember once lying doggo in a Soviet submarine for what seemed like ages to sink a US CVN with a wake-following torpedo as the task force passed over me. There were so many scenarios from Patrol Boat right up to a full nuclear exchange. Excellent stuff and this game is still on my PC.

"You'll never take me alive" said he,
And his ghost may be heard if you pass by that billabong
"Who'll come a Waltzing Matilda with me?"