kuluu-ffxi
Remaking the Final Fantasy XI client. The idea is to have a ~0.9:1 faithful reimplementation of the retail client without a lot of the performance jank and cruft that the original has, and then layer optional improvements, QoL, graphical improvements, UI/UX improvements etc., on top with a plugin system and hackable source code for players across various private servers. This approach allows people that just want to replace their familiar client with something slightly more modern/performant/cross-platform, all the way to entirely new experiences. There's at least one other project, not yet open-sourced, which is going more in the direction of adding all of the enhancements by default. https://github.com/jondwillis/kuluu-ffxi