My first sub sims were Silent Steel (not really a sim) and Sub Command. I got hooked on WWII sub sims with Silent Hunter II and Destroyer Command in 2002. I used to set up a home LAN so I could play head to head with a friend (dial-up internet wasn't so great in those days).
I bought SH3 on the day it released in March 2005 for $39.99 and have played it ever since. I tried SH4 (including the Uboot missions), SH5, and Uboat, but I keep coming back to SH3 for the best immersion. I can hardly believe that's been twenty years! So yes, I have earned the title "old man".