Felix Jones

That one time I made a Minecraft mod

I remember being quite impressed by the ComputerCraft mod (which is apparently open source now?), and it inspired me to attempt my first Minecraft mod that basically ripped off ComputerCraft and just did things the way past-Felix thought things should be done.

Whilst I was very familiar with Lua at the time, the first programming language I had begun to toy with was Ruby, and I had recently figured out how to embed CRuby (the full-fat Ruby interpreter, mruby wasn’t around at the time), so I thought I’d be really clever and make a mod that adds a “Ruby Block” to Minecraft, which would literally be a block of Ruby that executed Ruby script.

I still think Ruby would thematically be a hilarious choice for a Minecraft script language (but if you were to ask me with my sensible hat on, I’d give a different answer these days). I love the little pun of “code-block” crossing with “Minecraft block” to make it a literal block of Ruby code.

Rubies have a bit of history in Minecraft (does RubyDung count?) where they were going to be the original currency for villager trading (according to the unofficial Minecraft Wiki), so I guess this was me attempting to revive them without the ore block, but as something totally unexpected — in hindsight this is the type of out-of-the-box interpretation that tends to be most appreciated by my colleagues in Mojang Studios when it comes to Minecraft ideas, “Rubies aren’t an ore or gem, they’re something totally different”.

What went well?

I don’t have a good memory of what the mod making process was like back in the day, but my grasp of Java 8 was good from my experience working with Android, and I remember the tutorial I followed “how to add a block” got me to the point of having a block of “Ruby”, from there it was very easy to get JNI interfacing with my Ruby DLL and have a little “Hello World” activating, printing in the chat too. I think I had it run every tick? Didn’t get around to setting it up to activate on redstone.

I also got Ruby snippets working in the chat, so anything written in chat would be executed as Ruby. I had ideas of a scripting console (Quake style drop-down!) so one could script stuff in the game with Ruby.

What didn’t go well?

I identified a big flaw in what I was doing: I’d need to ship compiled binaries for my mod, and I only really had the means to debug a Windows DLL at the time, so immediately Mac and Linux fans would be missing out on my genius Ruby block.

Why didn’t I finish it?

The week after I began development, Mojang announces the Command Block.

The Command Block

At the time it appeared to me that the Command Block covered a significant chunk of use cases I had in mind for my Ruby block, and the rest of the use cases the Command Block didn’t cover was already achieved in ComputerCraft, so I didn’t have anything that would be impressive enough on its own, at most I was replacing Lua with an even less popular language.

The Command Block stomping on my idea stuck with me long enough that I stood in line at the Command Block panel of Minecon 2015 amongst a load of farting kids to ask the panelists for their thoughts on what would have been different if Command Blocks ran a full scripting language like Lua.

I never asked the question because all the time was taken up by the kids in front of me asking “What’s your favourite block” multiple times over.


I revisitted the Ruby powered Quake console part of this mod a number of times in later projects. From my experience of typing crude Ruby into Minecraft chat, I had realised that Ruby was oddly awesome for game commands.

A lot of the syntax felt like traditional game console commands, rather than typing out a program.

I wrote an article about my revelations regarding Ruby syntax for game commands, and reading that back (it’s cringe, please don’t read it) makes me still think Ruby would have been a great choice for game scripting.

This is one example from that page for teleporting the player if they are an admin:

Position.set x: 100, y: 110, z: 40 if Player.access == :admin

If I were to imagine how this would have looked if I finished my Ruby block mod it would probably be:

Player.teleport x: 100, y: 110, z: 40 if Player.team == "admin"

That’s just one idea. You could probably get the syntax into something looking really cool and easy to read for a non-programmer.

Would I revisit making this mod?

Probably not. I’m not even convinced Minecraft needs Command Blocks, let alone a full programming language in a block. ComputerCraft has that covered.

As for a proper scripting environment, I don’t think Ruby is the right choice: Lua would make more sense because of its prevelance, but the game has such a huge educational power that it would be a missed opportunity to not go for a language that provides a transferable skill.