Hardball 6 was my first baseball game but it wasn't really what got me interested in the idea of baseball sims.
As a teenager I loved all things cricket (only natural, being born and bred in New Zealand). A friend down the road came across a game called Card Cricket. It wasn't a particularly complex game, basically needing only the board below and a deck of cards (in fact, I quickly discovered that if I copied the board to a piece of paper I just needed that and a deck of cards - in time I needed only the cards and can still recite from memory the entire board and most of the attached commentary).
So, not a complex game but we loved it, and regularly got together to play out games with teams featuring us and our friends. In time we both got our own solo leagues going, though I was way more serious about it than he was, dedicating whole exercise books to match stats and career stats. I also created rules to make it more realistic (for hitting and bowling as well as adding contracts - based on performance - salary caps, pitch conditions, etc).
This kept me going for years and I still go back to it occasionally for nostalgia's sake - though sadly I've lost the notebook with all my extra rules. I came across the game recently in a second-hand shop, actually, and quickly bought it. Now I own the game but rarely play it whereas when I was younger I played it obsessively without ever owning it.
Anyhoo, I got into that before owning a computer and before I had much of an interest in baseball (my father came from the US, so I had some exposure to the game via my grandmother who was a lifelong Dodgers fan).
Sometime later, now with computer, I discovered Hardball 6 and loved, as The_Offspring187 did, "simming seasons until years in the future the guys who retired reentered the draft as younger versions of themselves." I also found a cheat with a couple amazingly-rated free agent pitchers who had zero stamina. Quick edit of the stamina rating and suddenly, voila, instant aces.
Time passed. New computer. Hardball 6 lost to the ethers.
But I found I wanted a sports sim that combined what I had in Card Cricket (ability to create fictional teams, etc, realism) with what I'd enjoyed in Hardball 6 (baseball, managing a team over the course of many seasons). None of the newer arcade-style games could scratch that itch. My research led me to the Strat-o-matic card game. Sadly it wasn't available in New Zealand. I saved up, sent the money to my grandparents in the US and asked them to buy and post to me.
The excitement when it arrived! The excitement which dimmed when I read through the rulebook and tried to sort out all the cards and figure out weather conditions and, well, just about everything else. It was just too complicated for a guy who'd gotten used to a computer organizing things in the background. Plus, I didn't follow baseball closely so I didn't know all the players. I played perhaps 2 games - each of which took me a couple hours - before I put it up on the shelf and left it to gather dust.
For quite some time after that I didn't try to scratch that baseball itch. Until one day I thought I'd see if the Hardball series had been updated. It hadn't been. Nothing great looked available for PC so I tried some of the console baseball games but didn't enjoy them and found their career modes lacking.
Then I discovered OOTP11. It looked absolutely amazing! I bought it. And quickly found myself struggling to understand how everything worked. I could tell it was the game I was looking for but I just couldn't get my head around it. Frustrated, I deleted it.
But over the following months my mind kept going back to OOTP. Oh, the possibilities! By the time I seriously considered the game again OOTP13 was out. This time I did things sensibly. I read the manual and took my time learning the game. A little while later I joined these forums, read some dynasty reports and lurked a lot.
Now OOTP is about the only game I play. I've logged thousands of hours so far and will log thousands more. It's everything I want in a sports sim and more, and every version just gets better and better. And the approachability of the development team is just amazing.
Bring on OOTP19!