Will It Host? / Microsoft Excel
Can you run a Minecraft server in Excel?
Yes. The process listening on port 25565 is EXCEL.EXE, and a vanilla Minecraft client connects to it and plays on it. This was the first build in the series, and the protocol code written for it went on to run three more.
How it works
VBA, speaking the Minecraft 1.8.9 protocol directly over a Windows socket, with the spreadsheet itself doing the job a server console usually does. No mods, no server jar, nothing proxying in front of it. The client is talking to Excel.
The part that nearly stopped it
There was nothing to build on. No Minecraft protocol library exists for VBA, so the handshake, the login exchange, chunk data and the keep-alives all had to be written by hand against the specification, in a language nobody has ever chosen for network programming.
What it cannot do
Minecraft 1.8.9 rather than anything current. In 1.8 a chunk is a flat byte array you can send uncompressed. Modern versions use palette-encoded, bit-packed longs and expect zlib, and VBA has no zlib.
Why this is possible at all
A Minecraft Java server is a smaller thing than its reputation suggests. It is a socket, a packet codec and a game loop. The client opens one TCP connection, sends a handshake naming its protocol version, moves through login into the play state, and from then on both sides exchange length-prefixed packets describing chunks, entities and movement. None of that needs a game engine. It needs something that can hold a socket open and put the right bytes on it in the right order, which is why Microsoft Excel can be made to do it and why the interesting part of each episode is the host rather than the protocol.
Every build in this series targets Minecraft 1.8.9 for one specific reason. In 1.8 a chunk is a flat byte array you can send uncompressed. From 1.9 onward chunk data is palette-encoded into bit-packed longs and the connection expects zlib, which is not something you can hand-write in VBA. 1.8.9 is the last release where the whole protocol is within reach of a scripting runtime that was never meant for it.
We have written both halves of that up properly: how the Minecraft server protocol works covers the wire format, and what a Minecraft server actually needs to run covers the four things a real one cannot do without.
Questions
Has anyone made Minecraft in Excel before?
Clones, yes. SethBling built a Minecraft clone inside Excel back in 2014 and it is worth watching. What we could not find was anyone who had made Excel serve the real game to a real, unmodified client. That is the difference here: this is not a lookalike drawn in cells, it is a spreadsheet answering the actual Minecraft protocol. If someone has done it before, send it over.
How do you run a Minecraft server in Excel?
VBA can call the Windows socket API, which is enough to listen on port 25565 and speak the Minecraft protocol by hand. Targeting 1.8.9 is what makes it practical, because 1.8 chunk data is a flat byte array that can go out uncompressed rather than the palette-encoded, zlib-compressed format modern versions expect. The full source is on GitHub.
The rest of the series
Or just host it properly
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