(WARNING: Long post ahead. Skip if you are sleepy or impatient or don't care.)
I first found out about Blockland back in May-ish 2006. Someone on a lego fansite forums posted a thread about TBM. I downloaded it, expected lots. I accidentally clicked on blockLand.exe instead of Play TBM.bat (blockLand.exe was the application for the early beta. The one were people's heads were round and graphics sucked.). So I join a server, and then one day I find out how to forward my ports. I do that, host a server, and me and this guy build an awesome house together. Then, someone from RTB joined and told us about how epic it was. I was like "AWESUM" and I downloaded RTB. At the time, the version was around 1.043-ish. So I played and played, until Retail was released. I was so mad at how I had to pay $20 at something that probably wasn't even that great. So I stuck with (RW) and RTB 1.045, and joined the 'Retail Rebellion'. Figures, the rebellion died before Blockland v8 came, so then I just tried the demo of Blockland retail. Boy was I wrong about my rebellion idea. I eventually grew tired of the demo limit, and I wanted to try more. So my friend let me loan his Blockland key for about 6 months. I LOVED BLOCKLAND, and the promises of v9's wrench events and tanks were great. So I bought it on January 1st, 2008, ID 3614. I still can't believe I'm still playing now :D
tl;dr: I started by someone telling me about TBM, accidentally clicked normal 0002, heard about RTB, downloaded that, played it, joined retail rebellion, rebellion died, tried Blockland retail demo, had friend loan me key to try more, and bought my own key.