On 12/21/2011 Yamagi Quake II 4.0 was released to celebrate the tenth anniveray of the release of the Quake II source under the terms of the GPLv2. Changes since 3.00 include:

- A major rewrite of the savegame system.
- Add a crash handler, printing a backtrace on Linux platforms.
- Add support for system wide installations.
- ctf was moved into a separate download.
- All open bugs were fixed.
- Fix spawnpoint selection if single player maps are loaded via console.
- Rename ~/.quake2 to ~/.yq2 to ease parallel installation with other Quake II clients.
- The client does no longer crash if the menu is opened while connecting to remote server.
- The game code received a code audit and major rework.

The rewrite of the save game system results in much more reliable savegame handling. Savegames shouldn´t break any longer if the game.so is rebuild or even altered. Since the savegame code is part of the game.so this only affects the "baseq2" game. New versions of the addons will be released in the future