My favorite memories where playing Blockland in my younger years (sorry if I'm being aa bit vague.) I've played Blockland an upwards of 6 years (I think?) and it's one of my favorite games, right alongside Minecraft. However, you can never quite relive that feeling of when you first experience something amazing. The time I spent playing the demo. That day I came home and my brothers told me our dad had bought Blockland for us. That first server, as clueless as I was, and as much as I got yelled at for just that reason. I'll never forget it.
More specifically, I remember playing Jaguar's Dogfight (I miss the Slopes :( ) with my brother almost all summer long. Also, back when I was more simple minded, I could spend a whole day on some Family RP. Then there was that time a hosted an Island Build and became the top server for a few days! There was also another island build I made with friends (which eventually got deleted/overwritten by accident >:( ) where I met and built with a lot of new players and made friends (none of which I know know, however.)
I could go on forever, now that I think about it. It really irks me when people say a childhood where you spend almost all your time playing video games is a childhood wasted. I agree that you shouldn't spend ALL your time playing video games, but I can honestly say that some of my fondest childhood memories are of playing video games, like Blockland.