Wouldn’t it be more in the spirit of this community to use a free and open source alternative to Minecraft like Classicube?

github.com/ClassiCube/ClassiCube

I discovered this one recently. As the name implies, it’s a reverse-engineered clone of early versions of the game. It has extremely low hardware requirements, which allow the client to run on virtually anything.

Here’s a list of supported server software:

www.classicube.net/server/host/

If you use MCGalaxy, then players will even be able to join your servers through their web browser.