Minecraft Pi Edition (2013)

It's unfortunate that this never really took off and was eventually discontinued. Pi Edition was only ever distributed as an ARMv6 executable for Linux on Raspberry Pi, without any source code, so it isn't nearly as moddable as the Java edition of the game. But it had a minimalistic modding API using a TCP protocol, and has libraries for many programming languages.

I remember playing with that. It was awesome as a little tech demo on the original Pi. I remember playing around with the modding API a little bit, doing things like making a rainbow of blocks follow behind my character, or spawning objects that I defined in code.

I was waiting for it to become more, but it just never did.